题解 | 【模板】前缀和

#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n, q;
    cin >> n >> q;
    
    // 读取数组
    vector<long long> prefix(n + 1, 0);  // 前缀和数组，0位置为0
    for(int i = 1; i <= n; i++) {
        int x;
        cin >> x;
        prefix[i] = prefix[i-1] + x;  // 计算前缀和
    }
    
    // 处理查询
    while(q--) {
        int l, r;
        cin >> l >> r;
        cout << prefix[r] - prefix[l-1] << endl;
    }
    
    return 0;
}

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int q = sc.nextInt();
        
        // 读取数组并计算前缀和
        long[] prefix = new long[n + 1];
        prefix[0] = 0;  // 0位置为0
        for(int i = 1; i <= n; i++) {
            prefix[i] = prefix[i-1] + sc.nextLong();
        }
        
        // 处理查询
        while(q-- > 0) {
            int l = sc.nextInt();
            int r = sc.nextInt();
            System.out.println(prefix[r] - prefix[l-1]);
        }
        
        sc.close();
    }
}

def main():
    n, q = map(int, input().split())
    
    # 读取数组并计算前缀和
    nums = list(map(int, input().split()))
    prefix = [0] * (n + 1)  # 前缀和数组，0位置为0
    for i in range(n):
        prefix[i + 1] = prefix[i] + nums[i]
    
    # 处理查询
    for _ in range(q):
        l, r = map(int, input().split())
        print(prefix[r] - prefix[l-1])

if __name__ == "__main__":
    main()