<p>Given an <code>m x n</code> binary matrix <code>mat</code>, return <em>the distance of the nearest </em><code>0</code><em> for each cell</em>.</p>

<p>The distance between two adjacent cells is <code>1</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/04/24/01-1-grid.jpg" style="width: 253px; height: 253px;" />
<pre>
<strong>Input:</strong> mat = [[0,0,0],[0,1,0],[0,0,0]]
<strong>Output:</strong> [[0,0,0],[0,1,0],[0,0,0]]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/04/24/01-2-grid.jpg" style="width: 253px; height: 253px;" />
<pre>
<strong>Input:</strong> mat = [[0,0,0],[0,1,0],[1,1,1]]
<strong>Output:</strong> [[0,0,0],[0,1,0],[1,2,1]]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == mat.length</code></li>
	<li><code>n == mat[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 10<sup>4</sup></code></li>
	<li><code>1 &lt;= m * n &lt;= 10<sup>4</sup></code></li>
	<li><code>mat[i][j]</code> is either <code>0</code> or <code>1</code>.</li>
	<li>There is at least one <code>0</code> in <code>mat</code>.</li>
</ul>

class Solution:
    def updateMatrix(self, mat: List[List[int]]) -> List[List[int]]:
        n = len(mat)
        m = len(mat[0])

        q = deque()
        res = [[-1 for x in range(m)] for y in range(n)]
        print(res)
        for i in range(n):
            for j in range(m):
                if mat[i][j] == 0:
                    q.append((i, j))
                    res[i][j] = 0
        
        def insertQ(r, c, dist):
            if r < 0 or c < 0 or r >= n or c >= m:
                return
            if res[r][c] >= 0:
                return
            q.append((r, c))
            res[r][c] = dist
        
        while q:
            r, c = q.popleft()
            d = res[r][c]
            
            insertQ(r+1, c, d+1)
            insertQ(r-1, c, d+1)
            insertQ(r, c+1, d+1)
            insertQ(r, c-1, d+1)
        
        return res
        
19800