洛谷P1162 填涂颜色——广搜

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

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

#include<iostream>
#include<queue>
using namespace std;
int xx[] = { 0,-1,0,1 };
int yy[] = { 1,0,-1,0 };
int mp[40][40];
bool vis[40][40];
int n;
int main()
{
  cin >> n;
  for (int i = 1; i <= n; i++)
  {
    for (int j = 1; j <= n; j++)
    {
      cin >> mp[i][j];
    }
  }
  queue<int>x;
  queue<int>y;
  x.push(0);
  y.push(0);
  vis[0][0] = 1;
  while (!x.empty())
  {
    int tx = x.front();
    int ty = y.front();
    for (int i = 0; i < 4; i++)
    {
      int dx = x.front() + xx[i];
      int dy = y.front() + yy[i];
      if (dx >= 0 && dx <= n + 1 && dy >= 0 && dy <= n + 1 && mp[dx][dy] == 0 && !vis[dx][dy])
      {
        x.push(dx);
        y.push(dy);
        vis[dx][dy] = 1;
      }
    }
    x.pop();
    y.pop();
  }
  for (int i = 1; i <= n; i++)
  {
    for (int j = 1; j <= n; j++)
    {
      if (mp[i][j] == 0 && vis[i][j] == 0)
      {
        cout << 2 << " ";
      }
      else
      {
        cout << mp[i][j] << " ";
      }
    }
    cout << endl;
  }
  return 0;
}