AcWing 795. Prefix sum (prefix sum, one-dimensional)

Question
idea: Change the time of n^2 to n. You can turn each number you input into a one-dimensional array sum of them. If you need someone, just subtract it directly.
Formula: s[i]=s[i-1]+a[i] s[r]-s[l-1]

Code:

#include<iostream>
#include<vector>
#include<algorithm> 

using namespace std;

const int N=1e5+10; 
int n,m;
int a[N],s[N];

int main()
{
    
    
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++)//注意从i=1开始 
	scanf("%d",&a[i]);
	for(int i=1;i<=n;i++) s[i]=s[i-1]+a[i];// 前缀和的初始化
	while(m--)
	{
    
    
		int l,r;
		scanf("%d%d",&l,&r);
		printf("%d\n",s[r]-s[l-1]);//区间和计算 
	 } 
	return 0;
}