hdu 1166 敌兵布阵（树状数组）

题意：区间和

思路：树状数组

#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;int n,c[50005];int lowbit(int i){return i&-i;
}void update(int i,int val){//更新函数while(i<=n){//注意这个n的变化，应该为最大值，具体题目自行变化。c[i]+=val;i+=lowbit(i);}
}int sum(int i){//求和函数int sum=0;while(i>0){sum+=c[i];i-=lowbit(i);}return sum;
}int main(){int t,a,b,i,j;char str[10];scanf("%d",&t);for(i=1;i<=t;++i){memset(c,0,sizeof(c));printf("Case %d:\n",i);scanf("%d",&n);for(j=1;j<=n;++j){scanf("%d",&b);update(j,b);}while(~scanf("%s",str)&&str[0]!='E'){scanf("%d%d",&a,&b);if(str[0]=='A')update(a,b);else if(str[0]=='S')update(a,-b);else printf("%d\n",sum(b)-sum(a-1));}}return 0;
}