hdu 1166 敌兵布阵

AC代码：

#include <iostream>
#include <cstdio>
using namespace std;

const int N = 50005;

struct node{
    int l,r,sum;
}tree[N<<2];
int a[N];

void build(int m,int l,int r){
    tree[m].l = l;
    tree[m].r = r;
    if(l == r){
        tree[m].sum = a[l];
        return ;
    }
    int mid = (l+r)>>1;
    build(m<<1,l,mid);
    build((m<<1)|1,mid+1,r);
    tree[m].sum = tree[m<<1].sum+tree[(m<<1)|1].sum;
}

void update(int m,int x,int val){
    if(tree[m].l == x && tree[m].r == x){
        tree[m].sum += val;
        return ;
    }
    int mid = (tree[m].l+tree[m].r)>>1;
    if(x <= mid)
        update(m<<1,x,val);
    else
        update((m<<1)|1,x,val);
    tree[m].sum = tree[m<<1].sum+tree[(m<<1)|1].sum;
}


int query(int m,int l,int r){
    if(tree[m].l == l && tree[m].r == r)
        return tree[m].sum;
    int mid = (tree[m].l+tree[m].r)>>1;
    if(r <= mid)
        return query(m<<1,l,r);
    if(l > mid)
        return query((m<<1)|1,l,r);
    return query(m<<1,l,mid)+query((m<<1)|1,mid+1,r);
}

int main(){
    int T,t = 1;
    scanf("%d",&T);
    while(T--){
        int n;
        scanf("%d",&n);
        for(int i = 1; i <= n; i++)
            scanf("%d",&a[i]);
        build(1,1,n);
        printf("Case %d:\n",t++);
        char op[10];
        int x,y;
        while(1){
            scanf("%s",op);
            if(op[0] == 'Q'){
                scanf("%d%d",&x,&y);
                printf("%d\n",query(1,x,y));
            }
            else if(op[0] == 'A'){
                scanf("%d%d",&x,&y);
                update(1,x,y);
            }
            else if(op[0] == 'S'){
                scanf("%d%d",&x,&y);
                update(1,x,-y);
            }
            else if(op[0] == 'E')
                break;
        }
    }
    return 0;
}