hdu-1166 敌兵布阵---树状数组模板

题目链接：

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

题目大意：

维护动态的区间和，单点更新，就是模板题

#include<iostream>
#include<algorithm>
#include<set>
#include<cstring>
#include<cstdio>
using namespace std;
const int maxn = 100000 + 10;
typedef long long ll;
int tree[maxn];
int n;
int lowbit(int x)
{
    return x & (-x);
}
void add(int x, int d)
{
    while(x <= n)
    {
        tree[x] += d;
        x += lowbit(x);
    }
}
ll sum(int x)
{
    ll ret = 0;
    while(x > 0)//此处等于0会导致无限循环
    {
        ret += tree[x];
        x -= lowbit(x);
    }
    return ret;
}
int main()
{
    int T, cases = 0;
    scanf("%d", &T);
    while(T--)
    {
        scanf("%d", &n);
        memset(tree, 0, sizeof(tree));
        int x, y;
        for(int i = 1; i <= n; i++)
        {
            scanf("%d", &x);
            add(i, x);
        }
        char s[8];
        printf("Case %d:
", ++cases);
        while(scanf("%s", s) && s[0] != 'E')
        {
            scanf("%d%d", &x, &y);
            if(s[0] == 'A')
            {
                add(x, y);
            }
            else if(s[0] == 'S')
            {
                add(x, -y);
            }
            else if(s[0] == 'Q')
            {
                ll ans = sum(y) - sum(x - 1);
                printf("%lld
", ans);
            }
        }
    }
}