敌兵布阵(树状数组)

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

树状数组模板题

#include <stdio.h>
#include <iostream>
#include <string>
#include <string.h>
using namespace std;
const int N=50005;
int a[N],c[N];
int n;
int lowbit(int x)
{
    return x&(-x);
}
int sum(int x)
{
    int ans = 0;
    while(x > 0)
    {
        ans+=c[x];
        x-=lowbit(x);
    }
    return ans;
}
void add(int x,int d)
{
    while(x <= n)
    {
        c[x]+=d;
        x+=lowbit(x);
    }
}
int main()
{
    int t,L,R;
    int x,d,cnt = 0;
    char str[20];
    scanf("%d",&t);
    while(t--)
    {
        cnt++;
        scanf("%d",&n);
        memset(a,0,sizeof(a));
        memset(c,0,sizeof(c));
        for (int i = 1; i <= n; i++)
        {
            scanf("%d",&a[i]);
            add(i,a[i]);
        }
        printf("Case %d:\n",cnt);
        while(scanf("%s",str))
        {
            if(str[0]=='E')
                break;
            else if(str[0]=='Q')
            {
                scanf("%d %d",&L,&R);
                printf("%d\n",sum(R)-sum(L-1));
            }
            else if(str[0]=='A')
            {
                scanf("%d %d",&x,&d);
                add(x,d);
            }
            else
            {
                scanf("%d %d",&x,&d);
                add(x,-d);
            }
        }
    }
    return 0;
}