<span>POJ2352 stars 修改某个位置上的值，查找一段区间的和（向上修改，向下统计）</span>

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <cstdio>
using namespace std;
#define MAXN 32005
int c[MAXN],level[MAXN];
int lowbit(int x)
{
    return x&(-x);
}
void update(int x,int num)
{
    while(x<=MAXN)
     {
         c[x]+=num;
         x+=lowbit(x);
     }
}
int getSum(int x)
{
    int s=0;
    while(x>0)
     {
         s+=c[x];
         x-=lowbit(x);
     }
    return s;
}

int main()
{
    int n,x,y;
    while(~scanf("%d",&n))
    {
        memset(c,0,sizeof(c));
        memset(level,0,sizeof(level));
        for(int i=0;i<n;i++)
        {
            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;
}