前缀和模板题。

#include <cstdio>

int fore[1000001];

int main(){
    int N, M;
    scanf("%d %d", &N, &M);
    int temp, n, m;
    for(int i = 1; i <= N; i ++){
        scanf("%d", &temp);
        fore[i] = fore[i - 1] + temp;
    }
    for(int i = 1; i <= M; i ++){
        scanf("%d %d", &m, &n);
        printf("%d\n", fore[n] - fore[m - 1]);
    }
    return 0;
}

#include<stdio.h>

int a[1000005] = { 0 };

int main()
{
    int m, n, N, M, c, i;
    scanf("%d%d", &N, &M);
    for (i = 1; i <= N; i++)
    {
        scanf("%d", &c);
        a[i] = a[i - 1] + c;
    }
    while (M--)
    {
        scanf("%d%d", &m, &n);
        printf("%d\n", a[n] - a[m - 1]);
    }
    return 0;
}