敌兵布阵 HDU

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
typedef long long LL;
const int N = 50005;
int n;
int l,r;
int t;
int x;
int a[N];
int tr[N<<2];
char s[10];
int lowbit(int x)
{
    return x & -x;
}
void add(int x, int c)
{
    for (int i = x; i <= n; i += lowbit(i)) 
        tr[i] += c;
}
int sum(int x)
{
    int res = 0;
    for (int i = x; i; i -= lowbit(i)) 
        res += tr[i];
    return res;
}
int main()
{    
    cin>>t;
    int kase=0;
    
    while(t--)
    {
        cin>>n;
        memset(tr,0,sizeof tr);
        for(int i=1;i<=n;i++)
            cin>>x,add(i,x);
        printf("Case %d:
", ++kase);
        while(cin>>s)
        {
            if(s[0]=='E')
                break;
            cin>>l>>r;
            if(s[0]=='A')
                add(l,r);
            else if(s[0]=='S')
                add(l,-r);
            else if(s[0]=='Q')
                cout<<sum(r)-sum(l-1)<<endl;
        }
    }
}