树状数组入门 之 hdu 1166

第一道树状数组。。。入门。。。线段树做法：代码见这里

//  [4/7/2014 Sjm]
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <string>
using namespace std;
const int MAX_N = 50000;
int bit[MAX_N + 1], n;

int mySum(int i)
{
    int sum = 0;
    while (i>0){
        sum += bit[i];
        i -= (i&(-i));
    }
    return sum;
}

void myAdd(int i, int x)
{
    while (i<=n) {
        bit[i] += x;
        i += (i&(-i));
    }
}

int main()
{
    //freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);
    int T;
    scanf("%d", &T);
    for (int i = 1; i <= T; i++)
    {
        memset(bit, 0, sizeof(bit));
        printf("Case %d:
", i);
        scanf("%d", &n);
        for (int j = 1; j <= n; j++) {
            int x;
            scanf("%d", &x);
            myAdd(j, x);
        }
        string str;
        while (cin>>str && ('E' != str[0]))
        {
            int a, b;
            scanf("%d %d", &a, &b);
            if ('Q' == str[0])
                printf("%d
", mySum(b) - mySum(a-1));
            else {
                if ('A' == str[0]) myAdd(a, b);
                else myAdd(a, -b);
            }
        }
    }
    return 0;
}