输入:

6
0 0 0 0 0 0
0 0 1 1 1 1
0 1 1 0 0 1
1 1 0 0 0 1
1 0 0 0 0 1
1 1 1 1 1 1

输出:

0 0 0 0 0 0
0 0 1 1 1 1
0 1 1 2 2 1
1 1 2 2 2 1
1 2 2 2 2 1
1 1 1 1 1 1

代码如下:

#include <iostream>
using namespace std;
const int N  = 40;
int mp[N][N], mps[N][N];

int n;


int dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0};

void dfs(int x, int y) {
	for (int i  = 0; i < 4; i++) {
		int xx = x + dx[i], yy = y + dy[i];
		if (xx < 0 || xx > n + 1 || yy < 0 || yy > n + 1 || mps[xx][yy])
			continue;
		mps[xx][yy] = 1;
		dfs(xx, yy);
	}
}



int main() {
	cin >> n;
	for (int i = 1; i <= n; i++)
		for (int j  = 1; j <= n; j++) {
			cin >> mp[i][j];
			mps[i][j] = mp[i][j];
		}
	dfs(0, 0);
	for (int i  = 1; i <= n; i++) {
		for (int j = 1; j <= n; j++) {
			if (mps[i][j])
				cout << mp[i][j] << " ";
			else
				cout << 2 << " ";
		}
		cout << endl;
	}
	return 0;

}