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 =  + ;
 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 = ;
     while(x > )//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 = ;
     scanf("%d", &T);
     while(T--)
     {
         scanf("%d", &n);
         memset(tree, , sizeof(tree));
         int x, y;
         for(int i = ; i <= n; i++)
         {
             scanf("%d", &x);
             add(i, x);
         }
         char s[];
         printf("Case %d:\n", ++cases);
         while(scanf("%s", s) && s[] != 'E')
         {
             scanf("%d%d", &x, &y);
             if(s[] == 'A')
             {
                 add(x, y);
             }
             else if(s[] == 'S')
             {
                 add(x, -y);
             }
             else if(s[] == 'Q')
             {
                 ll ans = sum(y) - sum(x - );
                 printf("%lld\n", ans);
             }
         }
     }
 }