HDU 1166 敌兵布阵(线段树)

　　基础树状数组,但我是用线段树解决这个问题的,线段树相对麻烦,但是单纯为了应用一下,毕竟学到这了

#include<iostream>
#include<cstdio>
#include<cstring>
#include<map>
using namespace std;
#define maxn 50005
#define lson p<<1
#define rson p<<1|1
struct NODE
{
    int l,r,sum;
} node[maxn<<4];
void build(int l,int r,int p)
{
    node[p].l = l,node[p].r = r;
    if(l == r)
    {
        int num;
        scanf("%d",&num);
        node[p].sum = num;
        return;
    }
    int mid = (l+r) >> 1;
    build(l,mid,lson);
    build(mid+1,r,rson);
    node[p].sum = node[lson].sum + node[rson].sum ;
}
int ask(int l,int r,int p)
{
    if(node[p].l == l && node[p].r == r)
    {
        return node[p].sum;
    }
    int mid = (node[p].l + node[p].r) >> 1;
    if(r <= mid) return ask(l,r,lson);
    else if(l >= mid+1) return ask(l,r,rson);
    else return ask(l,mid,lson) + ask(mid+1,r,rson);
}
void update(int num,int p,int op)
{
    if(node[p].l==node[p].r && node[p].l == num)
    {
        node[p].sum += op;
        return;
    }
    int mid = (node[p].l + node[p].r) >> 1;
    if(num <= mid)  update(num,lson,op);
    else if(num >= mid+1)  update(num,rson,op);
    else
    {
        update(num,lson,op);
        update(num,rson,op);
    }
    node[p].sum = node[lson].sum + node[rson].sum;
}
int main()
{
    int t;
    scanf("%d",&t);
    int tot = 0;
    while(t--)
    {
        int n;
        printf("Case %d:
",++tot);
        scanf("%d",&n);
        build(1,n,1);

        char op[20];
        while(~scanf("%s",op) && op[0] != 'E')
        if(op[0] == 'Q')
        {
            int l,r;
            scanf("%d%d",&l,&r);
            printf("%d
",ask(l,r,1));
        }
        else if(op[0] == 'A')
        {
            int num,opn;
            scanf("%d%d",&num,&opn);
            update(num,1,opn);
        }
        else
        {
            int num,opn;
            scanf("%d%d",&num,&opn);
            update(num,1,-opn);
        }
    }
    return 0;
}