/**

 *  @author           johnsondu

 *  @time             2015-8-22

 *  @type             Binary Index Tree

 *                      ignore the coordinate of y and

 *                      process as 1D conditions.

 *  @url              http://poj.org/problem?id=2352

 */

#include <iostream>

#include <cstdio>

#include <cmath>

#include <algorithm>

#include <cstring>

#include <string>

#include <stack>

#include <queue>

#include <map>

#include <vector>

using namespace std;

const int N = 15005;

const int M = 32010;

int level[N], c[M];

int lowbit(int x) {

    return (x & (-x)) ;

}

// 向上更新

void update(int x, int v) {

    while(x < M) {

        c[x] += v;

        x += lowbit(x);

    }

}

// 获取当前节点及下面的值的个数

int getSum(int x) {

    int sum = 0;

    while(x > 0) {

        sum += c[x];

        x -= lowbit(x);

    }

    return sum;

}

int main()

{

    int n, x, y;

    scanf ("%d", &n);

    memset(level, 0, sizeof(level));

    memset(c, 0, sizeof(c));

    for(int i = 1; i <= n; i ++) {

        scanf("%d%d", &x, &y);

        ++ level[getSum(x + 1)];

        update(x+1, 1);

    }

    for(int i = 0; i < n; i ++) {

        cout << level[i] << endl;

    }

    return 0;

}

附一篇经典翻译，学习 树状数组  http://www.hawstein.com/posts/binary-indexed-trees.html