樹狀數組模型

模板1：改點求段

http://acm.hdu.edu.cn/showproblem.php?pid=1166  

hdu 1166 敵兵布陣

#include<iostream>#include<cstdio>#include<cstring>using namespace std;int a[50004],n;char str[20];int lowbit(int i){return i&(-i);}int Sum(int i){int sum=0;while(i>=1){sum+=a[i];i-=lowbit(i);}return sum;}void Update(int i,int tem){while(i<=n){a[i]+=tem;i+=lowbit(i);}}int main(){int t,i,tem;int num=1;int x,y;scanf("%d",&t);while(t--){scanf("%d",&n);memset(a,0,sizeof(a));for(i=1;i<=n;i++){scanf("%d",&tem);Update(i,tem);}printf("Case %d:\n",num);num++;getchar();while(scanf("%s",str)!=EOF){if(str[0]=='E')break;scanf("%d%d",&x,&y);if(str[0]=='A')Update(x,y);elseif(str[0]=='S')Update(x,-y);elseprintf("%d\n",Sum(y)-Sum(x-1));}}return 0;}