敌兵布阵 HDU 1166

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

题目简单，直接套用线段树模板。

代码如下：

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <queue>
#include <cmath>
#include <map>
#include <stack>
#include <cstring>
using namespace std;
#define INF 0xfffffff
#define maxn 51000
#define lson rt<<1
#define rson rt<<1|1
int A[maxn];

struct node
{
  int l, r, s;
} tree[maxn<<2];

void build(int l, int r, int rt)
{
    tree[rt].l = l;
    tree[rt].r = r;

    if(l == r)
    {
        tree[rt].s = A[l];
        return ;
    }

    int mid = (l+r)/2;

    build(l, mid, lson);
    build(mid+1, r, rson);

    tree[rt].s = tree[lson].s + tree[rson].s;
}

void update(int pos, int val, int rt)
{
   tree[rt].s += val;

   if(tree[rt].l == tree[rt].r)
       return ;

    int mid = (tree[rt].l + tree[rt].r)/2;

    if(pos<=mid) update(pos, val, lson);
    else  update(pos, val, rson);
}

int query(int l, int r, int rt)
{
    if(tree[rt].l == l && r == tree[rt].r)
        return tree[rt].s;

     int mid = (tree[rt].l + tree[rt].r)/2;
     if(r<=mid) return query(l, r, lson);
     else if(l>mid) return query(l, r, rson);
     else
     {
        int lsum, rsum;
        lsum = query(l, mid, lson);
        rsum = query(mid+1, r, rson);
        return lsum+rsum;
     }
}

int main()
{
    int T, n, a, b, cnt=1;
    char op[20];

    scanf("%d", &T);

    while(T --)
    {
        scanf("%d", &n);

        for(int i=1; i<=n; i++)
            scanf("%d", &A[i]);

        build(1, n, 1);

         printf("Case %d:
",cnt++);

        while(scanf("%s", op),strcmp(op, "End"))
        {

            scanf("%d %d", &a, &b);

            if(op[0] == 'Q')
            {
                int ans = query(a, b, 1);
                printf("%d
", ans);
                continue;
            }

            if(op[0] == 'A')
                update(a, b, 1);
            else
                update(a, -b, 1);
        }

    }
    return 0;
}