POJ 2352——Stars（树状数组）

Stars

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 32738 Accepted: 14298

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

51 15 17 13 35 5

Sample Output

12110

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题目大意：

给定n个点的坐标，按y从小到大给出，如果y相同，则按x从小到大给出。求出比(x,y）都不大于的点的个数

思路：

貌似不需要什么思路。。。。BIT

#include<iostream>#include<cstring>#include<cstdio>#include<algorithm>#define ll long long#define M 32000+10using namespace std;int c[M],level[M];void update(int x,int v){    while(x<=M){        c[x]+=v;        x+=x&-x;    }}int getsum(int x){    int sum=0;    while(x>0){        sum+=c[x];        x-=x&-x;    }    return sum;}int main(){    int n;    scanf("%d",&n);    for(int i=0;i<n;++i){        int x,y;        scanf("%d %d",&x,&y);        x++;        level[getsum(x)]++;        update(x,1);    }    for(int i=0;i<n;++i){        printf("%d\n",level[i]);    }    return 0;}