题目链接：http://acm.nyist.edu.cn/JudgeOnline/problem.php?pid=108
emmm..线段树可以写，但是暴力可过
AC代码：
#include <cstdio>
#include <iostream>
#include <cstring>
#define maxn 1000005
using namespace std;
int a[maxn];
int main()
{
int n,m;
scanf("%d%d",&n,&m);
a[0] = 0;
for(int i=1;i<=n;i++){
scanf("%d",&a[i]);
a[i] = a[i-1] + a[i];
}
while(m--){
int c,b;
scanf("%d%d",&c,&b);
printf("%d\n",a[b]-a[c-1]);
}
return 0;
}