//exercise 4.1package fourthchapterexercise1;import java.util.Scanner;public class first {    public static void main(String[] args) {        // TODO Auto-generated method stub        int integer=0,sum=0,positive=0,negative=0;        Scanner in=new Scanner(System.in);        System.out.println("Enter an int value,the program exits if the input is 0:");        while(true){            integer=in.nextInt();            if(integer==0)                break;            else if(integer>0)                positive++;            else                negative++;            sum=sum+integer;        }        double average=(double)sum/(positive+negative);        System.out.println("The number of positives is "+positive);        System.out.println("The number of negatives is "+negative);        System.out.println("The total is "+sum);        System.out.println("The average is "+average);    }}//exercise 4.2package fourthchapterexercise1;import java.util.Scanner;public class second {    public static void main(String[] args) {        // TODO Auto-generated method stub        final int NUMBER_OF_QUESTIONS=10;                int correctCount=0;        int count=0;                long startTime=System.currentTimeMillis();                String output="";                Scanner in=new Scanner(System.in);                //The main program        while (count<NUMBER_OF_QUESTIONS){            //0-15 random number            int number1=(int)(Math.random()*15+1);            int number2=(int)(Math.random()*15+1);                                    //input expression            System.out.print("What is "+number1+" + "+number2+"? ");                        //get answer            int answer=in.nextInt();                        //judge answer            if(number1+number2==answer){                System.out.println("You are correct!");                correctCount++;            }            else                 System.out.println("Your answer is wrong.\n"+number1+" + "+number2+" sh"                        + "ould be "+(number1+number2));                        //count            count++;                        output +="\n"+number1+" + "+number2+"="+answer+((number1+number2==answer)?" cor"                    + "rect":" wrong");        }                long endTime=System.currentTimeMillis();        long testTime=endTime-startTime;                System.out.println("Correct count is "+correctCount+"\nTest time is "+testTime/1000+" seco"                + "nds\n"+output);    }}//exercise 4.3package fourthchapterexercise1;public class third {    public static void main(String[] args) {        // TODO Auto-generated method stub        System.out.println("千克\t\t英镑");        for(int i=0;i<100;i++){            System.out.println(2*i+1+"\t\t"+(2*i+1)*2.2);        }    }}//exercise 4.4package fourthchapterexercise1;public class fourth {    public static void main(String[] args) {        // TODO Auto-generated method stub        System.out.println("英里\t\t千米");        for(int i=1;i<=10;i++){            System.out.println(i+"\t\t"+i*1.609);        }    }}//exercise 4.5package fourthchapterexercise1;public class fifth {    public static void main(String[] args) {        // TODO Auto-generated method stub        System.out.println("千克\t\t镑\t\t磅\t\t千克");        int pound=20;        for(int i=0;i<100;i++){            System.out.println(2*i+1+"\t\t"+(int)((2*i+1)*2.2*100)/100.0+"\t"                    + "\t"+pound+"\t\t"+(int)(pound/2.2*100)/100.0);            pound+=5;        }    }}//exercise 4.6package fourthchapterexercise1;public class sixth {    public static void main(String[] args) {        // TODO Auto-generated method stub        System.out.println("英里\t\t千米\t\t英里\t\t千米");        int pound=20;        for(int i=0;i<10;i++){            System.out.println(i+"\t\t"+(int)(i*1.609*1000)/1000.0+"\t"                    + "\t"+pound+"\t\t"+(int)(pound/1.609*1000)/1000.0);            pound+=5;        }    }}//exercise 4.7package fourthchapterexercise1;public class seventh {    public static void main(String[] args) {        // TODO Auto-generated method stub        double tuition=10000;        for(int i=0;i<10;i++){            tuition *= (1+0.05);                    }        System.out.println("after ten year,tuition is "+tuition);                double sum=0;        for(int i=0;i<4;i++){            sum += tuition;            tuition *= (1+0.05);        }        System.out.println("tuition of four year is "+sum);    }}//exercise 4.8package fourthchapterexercise1;import java.util.Scanner;public class eighth {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("please input number of students is ");        int number =in.nextInt();        String maxname=null;        int max=0;        for(int i=0;i<number;i++){            System.out.print("please input student‘s name and score:");            String name =in.next();            int score=in.nextInt();            if(score>max)                maxname=name;        }        System.out.print("The most high score students name is :"+maxname);    }}//exercise 4.9package fourthchapterexercise1;import java.util.Scanner;public class ninth {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("please input number of students is: ");        int number =in.nextInt();        String maxname=null,secondname=null;        int max=0;        int secondhigh=0;        for(int i=0;i<number;i++){            System.out.print("please input student‘s name and score:");            String name =in.next();            int score=in.nextInt();            if(score>max){                maxname=name;                max=score;            }            if(score>secondhigh&&score!=max){                secondname=name;                secondhigh=score;            }                    }        System.out.println("The most high score students name is :"+maxname);        System.out.println("The second high score students name is :"+secondname);    }}//exercise 4.10package fourthchapterexercise1;import java.util.Scanner;public class tenth {    public static void main(String[] args) {        // TODO Auto-generated method stub        int count=0;        for (int i=100;i<=1000;i++){            if(i%5==0&&i%6==0){                System.out.print("\t"+i);                count++;                if(count%10==0)                    System.out.println();            }        }    }}//exercise 4.11package fourthchapterexercise2;public class first {    public static void main(String[] args) {        // TODO Auto-generated method stub        int count=0;        for (int i=100;i<=200;i++){            if(i%5==0^i%6==0){                System.out.print("\t"+i);                count++;                if(count%10==0)                    System.out.println();            }        }    }}//exercise 4.12package fourthchapterexercise2;public class second {    public static void main(String[] args) {        // TODO Auto-generated method stub        int n=1;        while(true){            if(n*n>12000){                System.out.println("The smallest integer is "+n);                break;            }            n++;        }    }}//exercise 4.13package fourthchapterexercise2;public class third {    public static void main(String[] args) {        // TODO Auto-generated method stub        int n=1;        while(true){            if(n*n*n>12000){                System.out.println("The smallest integer is "+(n-1));                break;            }            n++;        }    }}//exercise 4.14package fourthchapterexercise2;public class fourth {    public static void main(String[] args) {        // TODO Auto-generated method stub        int startascii=33;        int count=0;        while(startascii<=126){            char output=(char)startascii;            count++;            System.out.print("\t"+output);            if(count%10==0)                System.out.println();            startascii++;        }    }}//exercise 4.15package fourthchapterexercise2;import java.util.Scanner;public class fifth {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("please input two integer n1 and n2 :");        int n1=in.nextInt();        int n2=in.nextInt();        int min;        if(n1>n2)            min=n2;        else            min=n1;        while(true){            if(n1%min==0&&n2%min==0){                System.out.println("The greatest common divisor is "+min);                break;            }            min--;        }    }}//exercise 4.16package fourthchapterexercise2;import java.util.Scanner;public class sixth {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("please input integer:");        int integer=in.nextInt();        System.out.print("The factor is :");        while(true){            for(int i=2;i<=integer;i++){                if(integer%i==0){                    System.out.print(i);                    integer=integer/i;                    if(integer==1)                        System.out.print(".");                    else                        System.out.print(",");                    break;                }            }            if(integer==1)                break;        }    }}//exercise 4.17package fourthchapterexercise2;import java.util.Scanner;public class seventh {    public static void main(String[] args) {        // TODO Auto-generated method stub                Scanner in=new Scanner(System.in);                System.out.print("please input integer (0-15):");        int input =in.nextInt();                for(int i=1;i<=input;i++){                        for(int j=1;j<=input-i;j++){                if(j==input-i){                    System.out.print("\t");                    break;                }                System.out.print("\t ");            }                        for(int k=i;k>0;k--){                                if(k==1){                    System.out.print(k);                    break;                }                                System.out.print(k+"\t");            }                        for(int j=2;j<=i;j++){                System.out.print("\t"+j);            }                        System.out.println();        }    }}//exercise 4.18package fourthchapterexercise2;public class eighth {    public static void main(String[] args) {        // TODO Auto-generated method stub        //pattern 1        for(int i=1;i<=6;i++){            for(int j=1;j<=i;j++){                System.out.print(j+"\t");            }            System.out.println();        }                System.out.println();        System.out.println();                //pattern 2        for(int i=1;i<=6;i++){            for(int j=1;j<=7-i;j++){                System.out.print(j+"\t");            }            System.out.println();        }        System.out.println();        System.out.println();                //pattern 3        for(int i=1;i<=6;i++){            for(int j=1;j<=6-i;j++){                System.out.print(" \t");            }            for(int k=i;k>=1;k--){                System.out.print(k+"\t");            }            System.out.println();        }                System.out.println();        System.out.println();                //pattern 4        for(int i=1;i<=6;i++){            for(int k=2;k<=i;k++){                System.out.print(" \t");            }            for(int j=1;j<=7-i;j++){                System.out.print(j+"\t");            }            System.out.println();        }    }}//exercise 4.19package fourthchapterexercise2;public class ninth {    public static void main(String[] args) {        // TODO Auto-generated method stub        int integer;        for(int i=1;i<=8;i++){                        for(int j=1;j<=8-i;j++){                System.out.print("    ");            }            for(int j=1;j<=i;j++){                integer=(int)Math.pow(2, j-1);                System.out.printf("%4d",integer);            }            for(int k=i-1;k>=1;k--){                integer=(int)Math.pow(2, k-1);                System.out.printf("%4d",integer);            }                                System.out.println();        }    }    }//exercise 4-20package fourthchapterexercise3;public class first {    public static void main(String[] args) {        // TODO Auto-generated method stub                System.out.println("prime of 2 to 1000 is:");        int count=0;                for(int i=2;i<=1000;i++){            boolean isprime=true;                        for(int j=2;j<=i/2;j++){                if(i%j==0){                    isprime=false;                    break;                }            }                        if(isprime){                count++;                System.out.printf("%4d",i);            }                        if(count%8==0&&isprime)                System.out.println();        }    }}//exercise 4.21package fourthchapterexercise3;import java.util.Scanner;//This function is not a rigorous//The correctedpublic class second {    public static void main(String[] args) {        // TODO Auto-generated method stub                Scanner in=new Scanner(System.in);                System.out.print("please input loan amount:");        int loanamount=in.nextInt();                System.out.print("Number of years:");        int numberofyears=in.nextInt();        double interestrate=0.05;        int count;        System.out.println("Inerest Rate      Monthly payment       Total Payment");                //computational        for(count=0;count<=24;count++){                        double monthlyinterestrate=interestrate/12;                        //The monthly payment            double monthlypayment=(loanamount*monthlyinterestrate)/                    (1-1/Math.pow(1+monthlyinterestrate,numberofyears*12));                        //total payment            double totalpayment=monthlypayment*12*numberofyears;                        System.out.println((int)(interestrate*100000)/1000.0+"%\t\t  "+            (int)(monthlypayment*100)/100.0+"0\t\t"+(int)(totalpayment*100)/100.0);                        interestrate +=0.00125;        }    }}//exercise 4.22package fourthchapterexercise3;import java.util.Scanner;public class third {    public static void main(String[] args) {        // TODO Auto-generated method stub                Scanner in=new Scanner(System.in);                System.out.print("Loan Amount:");        int loanamount=in.nextInt();                System.out.print("Number of Years:");        int numberofyears=in.nextInt();                System.out.print("Annual Interest rate:");        double annualinterestrate=in.nextDouble();                double monthlyinterestrate=annualinterestrate/12;        double monthlypayment=(loanamount*monthlyinterestrate)/                (1-1/Math.pow(1+monthlyinterestrate,numberofyears*12));        double totalpayment=monthlypayment*12*numberofyears;                System.out.println("\nMonthly Payment:"+monthlypayment);        System.out.println("Total Payment"+totalpayment);        System.out.println();                double interest=0,principal;        double balance=loanamount;        System.out.println("Payment\t\tInterest\t\t        Principal\t\t        Balance");        for(int i=1;i<=numberofyears*12;i++){            interest=monthlyinterestrate*balance;            principal=monthlypayment-interest;            balance=balance-principal;            System.out.println(i+"\t\t"+interest+"\t\t"+principal+"\t\t"+balance);        }    }}//exercise 4.23package fourthchapterexercise3;public class fourth {    public static void main(String[] args) {        // TODO Auto-generated method stub        double sum=0;        for(int i=1;i<=5000;i++){            sum += 1.0/i;        }        System.out.println("This is from left to right:"+sum);                sum=0;        for(int i=5000;i>=1;i--){            sum += 1.0/i;        }        System.out.println("This is from right to left:"+sum);    }}//exercise 4.24package fourthchapterexercise3;public class fifth {    public static void main(String[] args) {        // TODO Auto-generated method stub        double sum=0;        double molecular=1;        double denominator=3;                for(int i=1;i<=49;i++){            sum += molecular/denominator;            molecular += 2;            denominator += 2;        }        System.out.println("result is "+sum);    }}//exercise 4.25package fourthchapterexercise3;public class sixth {    public static void main(String[] args) {        // TODO Auto-generated method stub        for(int i=10000;i<=100000;i += 10000){            double pi=0,sum=0;            for (int j=0;j<=i;j++){                sum =sum+Math.pow(-1,j)*(1.0/(2*j+1));            }            pi=4*sum;            System.out.print("when i="+i+",pi="+pi+"\n");        }    }}//exercise 4.26package fourthchapterexercise3;//The arithmetic is not good enoughpublic class seventh {    public static void main(String[] args) {        // TODO Auto-generated method stub        for(int i=10000;i<=100000;i +=10000){            double sum=1;            double generaltype=1;            for(int j=1;j<=i;j++){                for(int k=1;k<=j;k++){                    generaltype *= 1.0/k;                }                sum += generaltype;            }            System.out.println("When i="+i+",e="+sum);        }            }}//exercise 4.27package fourthchapterexercise3;public class eighth {    public static void main(String[] args) {        // TODO Auto-generated method stub        int count=0;        System.out.println("A leap year all in twenty-first Century is:");        for(int year=2001;year<=2100;year++){            if(year%4==0&&year%100!=0||year%400==0){                System.out.print(year+" ");                count++;                if(count%10==0)                    System.out.println();            }        }    }}//exercise 4.28package fourthchapterexercise3;import java.util.Scanner;public class ninth {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("please input year and days of week:");        int year=in.nextInt();        int january=in.nextInt();                //The calculation of the first day of the month is the day of the week        int february=(january+31)%7;        int march=(february+28)%7;        if(year%4==0&&year%100!=0||year%400==0)            march=(february+29)%7;                int april=(march+31)%7;        int may=(april+30)%7;        int june=(may+31)%7;        int july=(june+30)%7;        int august=(july+31)%7;        int september=(august+31)%7;        int october=(september+30)%7;        int november=(october+31)%7;        int december=(november+30)%7;                //matching week        String week=null;                switch(january){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("January 1, "+year+" is "+week);                switch(february){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("february 1, "+year+" is "+week);                switch(march){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("march 1, "+year+" is "+week);                switch(april){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("april 1, "+year+" is "+week);                switch(may){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("may 1, "+year+" is "+week);                switch(june){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("june 1, "+year+" is "+week);                switch(july){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("july 1, "+year+" is "+week);                switch(august){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("august 1, "+year+" is "+week);                switch(september){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("september 1, "+year+" is "+week);                switch(october){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("october 1, "+year+" is "+week);                switch(november){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("november 1, "+year+" is "+week);                switch(december){        case 0:            week="Sunday";            break;        case 1:            week="Monday";            break;        case 2:            week="Tuesday";            break;        case 3:            week="Wednesday";            break;        case 4:            week="Thursday";            break;        case 5:            week="Friday";            break;        case 6:            week="Saterday";            break;        default:            break;        }        System.out.println("december 1, "+year+" is "+week);    }}//exercise 4.29package fourthchapterexercise3;import java.util.Scanner;public class tenth {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);                System.out.print("please input year and days of week:");        int year=in.nextInt();        int january=in.nextInt();                //The calculation of the first day of the month is the day of the week        int february=(january+31)%7;        int march=(february+28)%7;        if(year%4==0&&year%100!=0||year%400==0)            march=(february+29)%7;                int april=(march+31)%7;        int may=(april+30)%7;        int june=(may+31)%7;        int july=(june+30)%7;        int august=(july+31)%7;        int september=(august+31)%7;        int october=(september+30)%7;        int november=(october+31)%7;        int december=(november+30)%7;                //January        System.out.println("\t\t     January"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                int count=1;        for(int i=0;i<january;i++){            System.out.print("   \t");        }                //wrap        int temp=january;                //A month has 31 days        for(count=1;count<=31;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");                        //February        System.out.println("\t\t     February"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                count=1;        for(int i=0;i<february;i++){            System.out.print("   \t");        }                //wrap        temp=february;                //A month has 28 or 29 days        int feb=28;        if(year%4==0&&year%100!=0||year%400==0)            feb=29;        for(count=1;count<=feb;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");                        //March        System.out.println("\t\t     March"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                count=1;        for(int i=0;i<march;i++){            System.out.print("   \t");        }                //wrap        temp=march;                //A month has 31 days        for(count=1;count<=31;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");                        //April        System.out.println("\t\t     April"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                count=1;        for(int i=0;i<april;i++){            System.out.print("   \t");        }                //wrap        temp=april;                //A month has 30 days        for(count=1;count<=30;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");                        //May        System.out.println("\t\t     May"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                count=1;        for(int i=0;i<may;i++){            System.out.print("   \t");        }                //wrap        temp=may;                //A month has 31 days        for(count=1;count<=31;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");                        //June        System.out.println("\t\t     June"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                count=1;        for(int i=0;i<june;i++){            System.out.print("   \t");        }                //wrap        temp=june;                //A month has 30 days        for(count=1;count<=30;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");                        //July        System.out.println("\t\t     July"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                count=1;        for(int i=0;i<july;i++){            System.out.print("   \t");        }                //wrap        temp=july;                //A month has 31 days        for(count=1;count<=31;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");                        //August        System.out.println("\t\t     August"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                count=1;        for(int i=0;i<august;i++){            System.out.print("   \t");        }                //wrap        temp=august;                //A month has 31 days        for(count=1;count<=31;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");                        //September        System.out.println("\t\t     September"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                count=1;        for(int i=0;i<september;i++){            System.out.print("   \t");        }                //wrap        temp=september;                //A month has 30 days        for(count=1;count<=30;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");                        //October        System.out.println("\t\t     October"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                count=1;        for(int i=0;i<october;i++){            System.out.print("   \t");        }                //wrap        temp=october;                //A month has 31 days        for(count=1;count<=31;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");                        //November        System.out.println("\t\t     November"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                count=1;        for(int i=0;i<november;i++){            System.out.print("   \t");        }                //wrap        temp=november;                //A month has 30 days        for(count=1;count<=30;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");                        //December        System.out.println("\t\t     December"+year+" \t");        System.out.println("----------------------------------------------------");        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");                count=1;        for(int i=0;i<december;i++){            System.out.print("   \t");        }                //wrap        temp=december;                //A month has 31 days        for(count=1;count<=31;count++){            if(temp%7==0){                System.out.println();                temp=0;            }            System.out.printf("%3d\t",count);            temp++;        }        System.out.println("\n");    }}//exercise 4.30package fourthchapterexercise4;import java.util.Scanner;public class first {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("please input money and annual interest rate and number of month:");        double monthlymoney=in.nextDouble();        double yearlyinterestrate=in.nextDouble();        double numberofmonth=in.nextDouble();                double monthlyinterestrate=yearlyinterestrate/12;        double sum=0;        for(int i=1;i<=numberofmonth;i++){            sum=(monthlymoney+sum)*(1+monthlyinterestrate);        }        System.out.print(numberofmonth+"months later,the money on account of "+sum);    }}//exercise 4.31package fourthchapterexercise4;import java.util.Scanner;public class second {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("Enter the initial deposit amount:");        double sum=in.nextDouble();        System.out.print("Enter annual percentage yiekd:");        double yearlyinterestrate=in.nextDouble();        System.out.print("Enter maturityperiod(number if months):");        double numberofmonth=in.nextDouble();                double monthlyinterestrate=yearlyinterestrate/1200;        System.out.println("Month\t\tCD Value");        for(int i=1;i<=numberofmonth;i++){            sum=sum*(1+monthlyinterestrate);            System.out.printf("%5d",i);            System.out.println("\t\t"+sum);        }    }}//exercise 4.32package fourthchapterexercise4;import java.util.Scanner;public class third {    public static void main(String[] args) {        // TODO Auto-generated method stub        int lottery=0;                //Generate an integer, the number of two integers is different        while (true){            lottery=(int)(Math.random()*90+10);            int first=lottery/10;            int second=lottery%10;            if(first!=second)                break;        }                Scanner in=new Scanner(System.in);                System.out.print("Enter your lottery pick (two digits):");        int guess =in.nextInt();                //separation lottery digit        int lotteryDigit1=lottery/10;        int lotteryDigit2=lottery%10;                //separation guess digit        int guessDigit1=guess/10;        int guessDigit2=guess%10;                System.out.println("The lottery number is "+lottery);                //judge        if (guess == lottery)            System.out.println("Exact match:you win $10000");        else if(guessDigit2==lotteryDigit1&&guessDigit1==lotteryDigit2)            System.out.println("Match all digits: you win $3000");        else if(guessDigit1==lotteryDigit1                ||guessDigit1==lotteryDigit2                ||guessDigit2==lotteryDigit1                ||guessDigit2==lotteryDigit2)            System.out.println("Match one digit:you win $ 1000");        else            System.out.println("Sorry,no match");    }}//exercise 4.33package fourthchapterexercise4;public class fourth {    public static void main(String[] args) {        // TODO Auto-generated method stub        System.out.print("Ten thousand the following numbers,perfect number:");        for(int i=1;i<=10000;i++){            int sum=0;            for (int j=1;j<i;j++){                if(i%j==0){                    sum=sum+j;                }            }            if(sum==i){                System.out.print(i+" ");            }        }    }}//exercise 4.34package fourthchapterexercise4;import java.util.Scanner;public class fifth {    public static void main(String[] args) {                // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);                int computercount=0;        int personcount=0;        while (true){            System.out.print("scissor(0),rock(1),paper(2):");            int input=in.nextInt();                        int computer=(int)(Math.random()*3);                        if(computer==0&&input==1){                System.out.println("The computer is scissor.You are rock.You win");                personcount++;                computercount=0;            }            else if (computer==0&&input==2){                System.out.println("The computer is scissor.You are paper.You lost.");                computercount++;                personcount=0;            }                            else if (computer==0&&input==0){                System.out.println("The computer is scissor.You are scissor.It is a draw.");                computercount=0;                personcount=0;            }                                        else if (computer==1&&input==0){                System.out.println("The computer is rock.You are scissor.You lost.");                computercount++;                personcount=0;            }                            else if (computer==1&&input==1){                System.out.println("The computer is rock.You are rock.It is a draw.");                computercount=0;                personcount=0;            }                            else if (computer==1&&input==2){                System.out.println("The computer is rock.You are paper.You win.");                personcount++;                computer=0;            }                                        else if (computer==2&&input==0){                System.out.println("The computer is paper.You are scissor.You win.");                personcount++;                computercount=0;            }                            else if (computer==2&&input==1){                System.out.println("The computer is paper.You are rock.You lost.");                computercount++;                personcount=0;            }                            else if (computer==2&&input==2){                System.out.println("The computer is paper.You are paper.It is a draw.");                computercount=0;                personcount=0;            }                        if(computercount==2){                System.out.println("The computer won two times.");                break;            }            if(personcount==2){                System.out.println("You won two times.");                break;            }            }    }}//exercise 4.35package fourthchapterexercise4;public class sixth {    public static void main(String[] args) {        // TODO Auto-generated method stub        double sum=0;        for(int i=1;i<=624;i++){            sum += 1/(Math.pow(i, 0.5)+Math.pow(i+1,0.5));        }        System.out.print("sum is "+sum);    }}//exercise 4.37package fourthchapterexercise4;import java.util.Scanner;public class seventh {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("input a integer(Decimal system):");        int integer=in.nextInt();        int count=0;        int temp=integer;        String number="";                //求出字符变成二进制后的长度        while (integer!=0 ){            int remainder=integer%2;            integer /=2;            number =number+(char)(remainder+48);            count++;        }                //转换在数组中        int newcount=count;        char a[]=new char[count];        while (temp!=0 ){            int remainder=temp%2;            temp /=2;            a[count-1]=(char)(remainder+48);            count--;        }                        for(int i=0;i<newcount;i++){            System.out.print(a[i]);        }        System.out.print("\n"+number);    }}//exercise 4.38package fourthchapterexercise4;import java.util.Scanner;public class eight {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("please input integer(Decimal system):");        int integer=in.nextInt();                String hexadecimal="";        while(integer!=0){            int temp=integer%16;            if(temp<=9&&temp>=0)                hexadecimal=(char)(temp+‘0‘)+hexadecimal;            else                 hexadecimal=(char)(temp-10+‘A‘)+hexadecimal;            integer=integer/16;        }                System.out.println("The hexadecimal is "+hexadecimal);    }}//exercise 4.39package fourthchapterexercise4;public class ninth {    public static void main(String[] args) {        // TODO Auto-generated method stub        double sum=0;        for(int i=0;i<=5000;i++){            sum=5000+i*0.08;            if(sum>=30000){                System.out.println("minimum sales is "+(i-1));                System.exit(0);            }        }                        for(int i=5000;i<=10000;i++    ){            sum=5000+5000*0.08+i*0.10;            if(sum>30000){                System.out.println("minimum sales is "+(i-1));                System.exit(0);            }        }        int i=10000;                        while (sum<30000){            sum=5000+5000*0.08+10000*0.10+i*0.12;            i++;        }                System.out.println("minimum sales is "+(i-1));        System.exit(0);    }}//exercise 4.40package fourthchapterexercise4;public class tenth {    public static void main(String[] args) {        // TODO Auto-generated method stub        int positive=0;        int negative=0;        for(int i=1;i<=1000000;i++){            int temp=(int)(Math.random()*2);            if(temp==0)                positive++;            else                 negative++;        }        System.out.println("The positive is "+positive);        System.out.println("The negative is "+negative);    }}//exercise 4.41package fourthchapterexercise5;import java.util.Scanner;public class first {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("Enter numbers: ");        int integer=in.nextInt();        int max=0;        int count=0;        while (integer!=0){            if(max<integer){                max=integer;                count=0;            }            if(max==integer){                count++;            }            integer=in.nextInt();        }                System.out.println("The large number is "+max);        System.out.println("The occurrence count of the largest number is "+count);            }}//exercise 4.43package fourthchapterexercise5;import java.util.Scanner;public class second {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("Enter the number of second :");        int seconds=in.nextInt();        while(true){                        try {                  //pause for a second                Thread.sleep(1000);                                  if((seconds-1)==0){                System.out.println("Stopped");                break;                }                if((seconds-1)==1){                    System.out.println((seconds-1)+" second remaining");                    seconds--;                    continue;                }                System.out.println((seconds-1)+" seconds remaining");                                seconds--;                            //format                } catch (InterruptedException e) {                  //If abnormal, the output to the console                e.printStackTrace();              }                                            }            }}//exercise 4.44package fourthchapterexercise5;import java.util.Scanner;public class third {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);                int count=0;                for(int i=1;i<=1000000;i++){            double x=Math.random()*2-1;            double y=Math.random()*2-1;                        double distance1=Math.pow((x*x+y*y), 0.5);            double distance2=Math.pow((x-1)*(x-1)+(y-1)*(y-1),0.5);                        if(distance1>distance2&&x>0&&y>0)                count++;            if(x<0)                count++;        }                double chance=count/1000000.0;        System.out.println("The chance is "+(int)(chance*10000)/100.0+"%");    }}//exercise 4.45package fourthchapterexercise5;public class fourth {    public static void main(String[] args) {        // TODO Auto-generated method stub        int count=0;        for(int i=1;i<=7;i++){            for(int j=1;j<=7;j++){                if(i!=j){                    System.out.println(i+" "+j);                    count++;                }            }        }        System.out.println("The numbers of combination is "+count);    }}//exercise 4.46package fourthchapterexercise5;import java.util.Scanner;public class fifth {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner in=new Scanner(System.in);        System.out.print("Enter an integer:");        int integer =in.nextInt();                //Judgment is a positive or negative number        boolean judge=false;        if(integer<0){            integer=-integer;            judge=true;        }                //Convert decimal number to a binary number        int count=0;        String decimal="";        while(integer!=0){            int temp=integer%2;            decimal=(char)(temp+‘0‘)+decimal;            integer=integer/2;            count++;        }                for(int i=1;i<=16-count;i++){            decimal=‘0‘+decimal;        }                //Judgment is a positive or negative number        if(judge){            char []decimalarr=decimal.toCharArray();            for(int i=0;i<decimalarr.length;i++){                if(decimalarr[i]==‘0‘)                    decimalarr[i]=‘1‘;                else                    decimalarr[i]=‘0‘;            }            for(int i=decimalarr.length-1;i>=0;i--){                if(decimalarr[i]==‘1‘){                    decimalarr[i]=‘0‘;                }                else{                    decimalarr[i]=‘1‘;                    break;                }            }            System.out.print("The bits are ");            for(int i=0;i<decimalarr.length;i++){                System.out.print(decimalarr[i]);            }        }        else            System.out.println("The bits are "+decimal);                    }}