51Nod 1081 子段求和

题目链接：http://www.51nod.com/Challenge/Problem.html#problemId=1081

#include <iostream>
#include <cstdio>

using namespace std;

typedef long long ll;

const int N = 50010;

int a[N];
ll s[N];

int main()
{
    int n;
    scanf("%d", &n);
    
    for (int i = 1; i <= n; i++)
    {
        scanf("%d", &a[i]);
        s[i] = s[i - 1] + a[i];
    }
    
    int m;
    scanf("%d", &m);
    
    for (int i = 0; i < m; i++)
    {
        int left, len;
        scanf("%d%d", &left, &len);
        int right = left + len - 1;
        printf("%lld\n", s[right] - s[left - 1]);
    }
    
    return 0;
}