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hdu 1541 Stars 树状数组

2024-07-11 14:20:57   230人阅读

链接：http://acm.hdu.edu.cn/showproblem.php?pid=1541

 

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 4292    Accepted Submission(s): 1711


Problem Description
Astronomers often examine star maps where stars are represented by points on a plane and each star has Cartesian coordinates. Let the level of a star be an amount of the stars that are not higher and not to the right of the given star. Astronomers want to know the distribution of the levels of the stars. 



For example, look at the map shown on the figure above. Level of the star number 5 is equal to 3 (it‘s formed by three stars with a numbers 1, 2 and 4). And the levels of the stars numbered by 2 and 4 are 1. At this map there are only one star of the level 0, two stars of the level 1, one star of the level 2, and one star of the level 3. 

You are to write a program that will count the amounts of the stars of each level on a given map.
 

 

Input
The first line of the input file contains a number of stars N (1<=N<=15000). The following N lines describe coordinates of stars (two integers X and Y per line separated by a space, 0<=X,Y<=32000). There can be only one star at one point of the plane. Stars are listed in ascending order of Y coordinate. Stars with equal Y coordinates are listed in ascending order of X coordinate.
 

 

Output
The output should contain N lines, one number per line. The first line contains amount of stars of the level 0, the second does amount of stars of the level 1 and so on, the last line contains amount of stars of the level N-1.
 

 

Sample Input
5
1 1
5 1
7 1
3 3
5 5
 

 

Sample Output
1
2
1
1
0
 
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题意不是那么好理解，先说下，就是求每个点的左下角有多少个点，那么它的lev就是几
y轴已经按递增顺序给出，就不用管了
还有，树状数组不能处理0的情况，但是题目中0<=X,Y<=32000，显然为一坑标
要把下标加一
 
贴个代码：
#include <stdio.h>#include <string.h>#include <stdlib.h>#include <map>#define Maxx 32010#define N 15010int n;int c[Maxx];int str[N];int Lowbit(int x){    return x&(-x);}void Update(int x){    while(x<=Maxx)    {        c[x]++;        x+=Lowbit(x);    }}int Sum(int x){    int s=0;    while(x>0)    {        s+=c[x];        x-=Lowbit(x);    }    return s;}int main(){    int i,j,a,b;        while(scanf("%d",&n)!=EOF)    {        memset(c,0,sizeof(c));        memset(str,0,sizeof(str));        //for(i=0;i<n;i++)str[i]=0;        for(i=0; i<n; i++)        {            scanf("%d%d",&a,&b);            str[Sum(a+1)]++;            Update(a+1);        }        for(i=0; i<n; i++)        {            printf("%d\n",str[i]);        }    }    return 0;}

　　


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