n = int(input())
ls = [0]+ list(map(int, input().split()))
sumls = [0]*(n+1)
for i in range(1,n+1):
    sumls[i] = sumls[i-1]+ls[i]

k = int(input())
for i in range(k):
    l,r = map(int, input().split())
    print(sumls[r]-sumls[l-1])

from itertools import accumulate

n = int(input())
arr = list(map(int, input().split()))
k = int(input())

S = [0] + list(accumulate(arr))

for _ in range(k):
    l, r = map(int, input().split())
    print(S[r] - S[l - 1])

#include<bits/stdc++.h>
using namespace std;

const int N=1e5+10;
int n,q;
int arr[N];
int prefinx[N];
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>arr[i];
	}
	for(int i=1;i<=n;i++){
		prefinx[i]=prefinx[i-1]+arr[i]; 
	}
	cin>>q;
	while(q--){
		int l,r;
		cin>>l>>r;
		cout<<prefinx[r]-prefinx[l-1]<<endl;
	}
	return 0;	
} 

帮忙看看有什么可以优化嘛👀️

//用全能头
#include <bits/stdc++.h>
using namespace std;

int main()
{
    //输入数组长度n，cir再赋一遍
    int n, cir;
    cin >> n;
    cir = n;
    //初始化数组number、sum还有累计和add
    //最后前缀和减需要i-1位所以index0拿来做被减头
    int number[n] = {0};
    int sum[n] = {0};
    sum[0] = 0;
    int add = 0;
    //循环输入数组，注意sum从第二开始赋值
    while(cir)
    {
        cin >> number[n-cir];
        add += number[n-cir];
        sum[n-cir+1] = add;
        cir--;
    }
    //输入多少组测试times
    int times = 0;
    cin >> times;
    //输入左右索引l，r
    int l, r;
    //运算后按格式输出
    while(times)
    {
        cin >> l;
        cin >> r;
        cout << sum[r] - sum[l-1] << endl;
        times--;
    }
}

#include<bits/stdc++.h>
using namespace std;
const int N = 1e5+10;
int n,x;
int a[N],sum[N];

int main(){
	cin.tie(0);
	cout.tie(0);
	
	
	cin>>n;
	for(int i=1; i<=n; i++){
		cin>>a[i]; 
	}
	
	sum[1] = a[1];
	for(int i=2; i<=n; i++){
		sum[i]=a[i]+sum[i-1];
	}
	
	cin>>x;
	while(x--){
		int l,r;
		cin>>l>>r;
		cout<<sum[r]-sum[l-1]<<endl;
	}
	
	return 0;
}