不用数组的题解！

判断是不是边缘就行了，不需要数组储存

#include <iostream>
using namespace std;
int sum;
int main(){
    int n, m;
    cin >> n >> m;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            int x;
            cin >> x;
            if(i == 1 || i == n || j == 1 || j == m) sum += x;
        }
    }cout << sum;
    
    return 0;
}