题解

#include<iostream>
#include<cmath>
using namespace std;
int s[100009],a[100009];
int main(){
	int n,m;
	cin>>n>>m;
	s[0]=0;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		s[i]=s[i-1]+a[i];
	}
	while(m--){
		int L,R;
		cin>>L>>R;
		cout<<s[R]-s[L-1]<<endl;
	}
	return 0;
}