poj_2352树状数组

因为y已经排好序了，用x坐标建立一维树状数组

#include<iostream>#include<cstdio>#include<cstring>using namespace std;int n;int a[32001];int lev[15001];int lowbit(int x){    return x&(-x);}int sum(int x){    int ret=0;    while(x>0)    {        ret+=a[x];        x-=lowbit(x);    }    return ret;}void add(int x,int d){    while(x<=32001)    {        a[x]+=d;        if(x!=0)        x+=lowbit(x);        else break;    }}int main(){    while(scanf("%d",&n)!=EOF){    memset(a,0,sizeof(a));    memset(lev,0,sizeof(lev));    int b,c;    for(int i=0; i<n; i++)    {        scanf("%d%d",&b,&c);        //add(b,1);        b++;        lev[sum(b)]++;        add(b,1);    }    for(int i=0; i<n; i++)        printf("%d\n",lev[i]);    }    return 0;}