题解

#include <iostream>
using namespace std;
typedef long long ll;
const int N = 1e3;
ll n, m, c;
ll a[N][N];
int main(){
    cin >> n >> m >> c;
    for(int i=1; i<=n; i++){
        for(int j=1; j<=m; j++){
            ll temp;
            cin >> temp;
            a[i][j] = a[i-1][j] + a[i][j-1] - a[i-1][j-1] + temp;
        }
    }
    ll mx = 0;
    ll x = 0;
    ll y = 0;
    for(int i=0; i+c<n; i++){
        for(int j=0; j+c<m; j++){
            ll num = a[i+c][j+c] - a[i][j+c] - a[i+c][j] + a[i][j];
            if(mx < num){
                mx = num;
                x = i + 1;
                y = j + 1;
            }
        }
    }
    cout << x << " " << y << endl;
    return 0;
}