以下为代码

#include<iostream>
#include<algorithm>
#include<cstring>

using namespace std;

int main() {
    int n;
    int a, b, c;
    int w[15][15];
    int h[15][15][15][15];
    
    
    cin >> n >> a >> b >> c;
    while (a != 0 || b != 0 || c != 0) {
        w[a][b] = c;
        cin >> a >> b >> c;
    }
    
    for(int i = 1;i <= n; i++) for(int j = 1;j <= n; j++) for(int k = 1; k <= n; k++) for(int l = 1;l <= n; l++) {
        h[i][j][k][l] = max(max(h[i - 1][j][k - 1][l], h[i][j - 1][k][l - 1]),max(h[i - 1][j][k][l - 1], h[i][j - 1][k - 1][l])) + w[i][j] + w[k][l];;
        if(i == k && l == j) h[i][j][k][l] -= w[i][j];
    }
    
    cout << h[n][n][n][n];
    
    return 0;
}