class Solution

 {

 public:

     vector<vector<int>> updateMatrix(vector<vector<int>>& matrix)

     {

         int n = matrix.size(), m = matrix[].size();

         vector<vector<int>> vis(n, vector<int>(m, ));

         vector<vector<int>> d(n, vector<int>(m, 0x3f3f3f3f));

         queue<pair<int, int>> q;

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

         for (int i = ; i < n; i++)

         {

             for (int j = ; j < m; j++)

             {

                 if (matrix[i][j] == )

                 {

                     q.push(pair<int, int>(i, j));

                     vis[i][j] = ;

                     d[i][j] = ;

                 }

             }

         }

         while (!q.empty())

         {

             pair<int, int> tmp = q.front();

             q.pop();

             int x = tmp.first, y = tmp.second;

             for (int i = ; i < ; i++)

             {

                 int nx = x + dx[i], ny = y + dy[i];

                 if (nx >=  && nx < n && ny >=  && ny < m && !vis[nx][ny])

                 {

                     vis[nx][ny] = ;

                     d[nx][ny] = d[x][y] + ;

                     q.push(pair<int, int>(nx, ny));

                 }

             }

         }

         return d;

     }

 };