知识点:

复合类型:

二维数组。

#include <iostream>
using namespace std;

int main() {
    int n, m;
    int sum = 0;

    cin >> n >> m;
    int arr[n][m];

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> arr[i][j];
            if (arr[i][j] > 0) {
                sum += arr[i][j];
            }
        }
    }

    cout << sum;

    return 0;
}