首页 > 代码库 > [容斥原理] hdu 4135 Co-prime
[容斥原理] hdu 4135 Co-prime
题目链接:
http://acm.hdu.edu.cn/showproblem.php?pid=4135
Co-prime
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 1176 Accepted Submission(s): 427
Problem Description
Given a number N, you are asked to count the number of integers between A and B inclusive which are relatively prime to N.
Two integers are said to be co-prime or relatively prime if they have no common positive divisors other than 1 or, equivalently, if their greatest common divisor is 1. The number 1 is relatively prime to every integer.
Two integers are said to be co-prime or relatively prime if they have no common positive divisors other than 1 or, equivalently, if their greatest common divisor is 1. The number 1 is relatively prime to every integer.
Input
The first line on input contains T (0 < T <= 100) the number of test cases, each of the next T lines contains three integers A, B, N where (1 <= A <= B <= 1015) and (1 <=N <= 109).
Output
For each test case, print the number of integers between A and B inclusive which are relatively prime to N. Follow the output format below.
Sample Input
2 1 10 2 3 15 5
Sample Output
Case #1: 5 Case #2: 10HintIn the first test case, the five integers in range [1,10] which are relatively prime to 2 are {1,3,5,7,9}.
Source
The Third Lebanese Collegiate Programming Contest
Recommend
lcy
题目意思:
给一个a,b,n求在[a,b]内有多少个与n互质的数。
解题思路:
简单的容斥原理。
反面思考,先求出与n不互质的,也就是包含n的质因数的。然后就可以想到先把n分解质因数。然后可以想到先预处理1000000内的质数。
然后求出1~b满足要求的个数,减去1~a-1满足要求的个数,答案即为最后结果。
代码:
//#include<CSpreadSheet.h> #include<iostream> #include<cmath> #include<cstdio> #include<sstream> #include<cstdlib> #include<string> #include<string.h> #include<cstring> #include<algorithm> #include<vector> #include<map> #include<set> #include<stack> #include<list> #include<queue> #include<ctime> #include<bitset> #include<cmath> #define eps 1e-6 #define INF 0x3f3f3f3f #define PI acos(-1.0) #define ll __int64 #define LL long long #define lson l,m,(rt<<1) #define rson m+1,r,(rt<<1)|1 #define M 1000000007 //#pragma comment(linker, "/STACK:1024000000,1024000000") using namespace std; #define N 1000000 int prime[130000],cnt; bool isprime[N+10]; int pp[110000],cnt0; ll a,b,n,ans1,ans2; void init() //预处理出1~1000000内的质数 { cnt=0; for(int i=1;i<=N;i++) isprime[i]=true; for(int i=2;i<=N;i++) { if(!isprime[i]) continue; prime[++cnt]=i; for(int j=i*2;j<=N;j+=i) isprime[j]=false; } //printf("cnt:%d\n",cnt); } void Cal(ll cur) //分解出cur的质因数 { cnt0=0; for(int i=1;prime[i]*prime[i]<=cur;i++) { if(cur%prime[i]==0) { pp[++cnt0]=prime[i]; while(!(cur%prime[i])) cur/=prime[i]; } } if(cur!=1) pp[++cnt0]=cur; } void dfs(ll hav,int cur,int num) //容斥原理求出互质的 { if(cur>cnt0||(hav>a&&hav>b)) return ; for(int i=cur;i<=cnt0;i++) { ll temp=hav*pp[i]; if(num&1) { ans1-=b/temp; ans2-=a/temp; } else { ans1+=b/temp; ans2+=a/temp; } dfs(temp,i+1,num+1); } } int main() { //freopen("in.txt","r",stdin); //freopen("out.txt","w",stdout); init(); //system("pause"); int t; scanf("%d",&t); for(int ca=1;ca<=t;ca++) { scanf("%I64d%I64d%I64d",&a,&b,&n); Cal(n); //printf("cnt0:%d\n",cnt0); a--; ans1=b,ans2=a; for(int i=1;i<=cnt0;i++) { ans1-=b/pp[i]; ans2-=a/pp[i]; dfs(pp[i],i+1,2); } printf("Case #%d: %I64d\n",ca,ans1-ans2); } return 0; }
声明:以上内容来自用户投稿及互联网公开渠道收集整理发布,本网站不拥有所有权,未作人工编辑处理,也不承担相关法律责任,若内容有误或涉及侵权可进行投诉: 投诉/举报 工作人员会在5个工作日内联系你,一经查实,本站将立刻删除涉嫌侵权内容。