Even Parity Uva 11464 ,

写的时候多打了个叹号... 坑了很久

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;


int main(){

    int answer = 0;

    int n;
    scanf("%d", &n);
    int mat[17][17];
    int vis[17][17];
    memset(vis, 0, sizeof(mat));
    memset(mat, 0, sizeof(mat));

    for (int i = 0; i < n+2; i++){
        for (int j = 0; j < n+2; j++){
            if (i == 0 || i == n+1 || j == 0 || j == n+1) {
                mat[i][j] = 0;
                vis[i][j] = 1;
            }
        }
    }

    for (int row = 1; row <= n; row++){
        for (int col = 1; col <= n; col++){
            cin >> mat[row][col];
            if (mat[row][col]) vis[row][col] = 1;
            
        }
    }
    for (;;){
        bool done = true;
        for (int row = 1; row <= n; row++){
            for (int col = 1; col <= n; col++){
                char u = 0;
                if (vis[row - 1][col]) u++;
                if (vis[row + 1][col]) u++;
                if (vis[row][col + 1]) u++;
                if (vis[row][col - 1]) u++;
                char sum = mat[row - 1][col] + mat[row + 1][col] + mat[row][col + 1] + mat[row][col - 1];
                if (u == 4 && (sum % 2)) answer = -1;
                else if (u == 3 && !(sum % 2)) {
                    if (!vis[row - 1][col]){
                        vis[row - 1][col] = 1;
                    }
                    else if (!vis[row + 1][col]){
                        vis[row + 1][col] = 1;
                    }
                    else if (!vis[row][col + 1]){
                        vis[row][col + 1] = 1;
                    }
                    else{
                        vis[row][col - 1] = 1;
                    }
                }
                else if (u == 3 && (sum % 2)){
                    if (answer != -1) {
                        done = false;
                        answer++;
                    }
                    if (!vis[row - 1][col]){
                        vis[row - 1][col] = 1;
                        mat[row - 1][col] = 1;
                    }
                    else if (!vis[row + 1][col]){
                        vis[row + 1][col] = 1;
                        mat[row + 1][col] = 1;
                    }
                    else if (!vis[row][col + 1]){
                        vis[row][col + 1] = 1;
                        mat[row][col + 1] = 1;
                    }
                    else{
                        vis[row][col - 1] = 1;
                        mat[row][col - 1] = 1;
                    }

                }
            }
        }
        if (done) break;
    }
    printf("%d", answer);

    return 0;
}