题解 | 【模板】二维前缀和

#include <stdio.h>

int main(void) {
    int n, m, q;    //行， 列，
    scanf("%d%d%d", &n, &m, &q);

    long long a[n][m];
    long long prefix[n + 1][m + 1];
    for (int i = 0; i <= n; i++)
        for (int j = 0; j <= m; j++)
            prefix[i][j] = 0;

    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++) {
            scanf("%lld", &a[i][j]);
            prefix[i + 1][j + 1] = prefix[i + 1][j] + prefix[i][j + 1] - prefix[i][j] + a[i][j];
        }

    for (int i = 0; i < q; i++) {
        long long x1, y1, x2, y2;
        scanf("%lld%lld%lld%lld", &x1, &y1, &x2, &y2);

        long long sum = prefix[x2][y2] - prefix[x1 - 1][y2] - prefix[x2][y1 - 1] + prefix[x1 - 1][y1 - 1];
        printf("%lld\n", sum);
    }
    return 0;
}