<p>Given an <code>m x n</code> binary <code>matrix</code> filled with <code>0</code>&#39;s and <code>1</code>&#39;s, <em>find the largest square containing only</em> <code>1</code>&#39;s <em>and return its area</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/11/26/max1grid.jpg" style="width: 400px; height: 319px;" />
<pre>
<strong>Input:</strong> matrix = [[&quot;1&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;],[&quot;1&quot;,&quot;0&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;],[&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;],[&quot;1&quot;,&quot;0&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;]]
<strong>Output:</strong> 4
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/11/26/max2grid.jpg" style="width: 165px; height: 165px;" />
<pre>
<strong>Input:</strong> matrix = [[&quot;0&quot;,&quot;1&quot;],[&quot;1&quot;,&quot;0&quot;]]
<strong>Output:</strong> 1
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> matrix = [[&quot;0&quot;]]
<strong>Output:</strong> 0
</pre>

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

<ul>
	<li><code>m == matrix.length</code></li>
	<li><code>n == matrix[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 300</code></li>
	<li><code>matrix[i][j]</code> is <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
</ul>

class Solution:
    def maximalSquare(self, matrix: List[List[str]]) -> int:
        max_square = 0
        for r in range(len(matrix)):
            for c in range(len(matrix[0])):
                if int(matrix[r][c]):
                    max_square = max(max_square, 1)
                    if r == 0 or c == 0:
                        continue 
                    
                    if int(matrix[r-1][c-1]) and int(matrix[r-1][c]) and int(matrix[r][c-1]):
                        matrix[r][c] = str(min(int(matrix[r-1][c-1]),int(matrix[r-1][c]),int(matrix[r][c-1])) + 1) 
                        max_square = max(max_square, int(matrix[r][c]))
        
        print(matrix, max_square)
        # ['1', '0', '1', '0', '0']
        # ['1', '0', '1', '1', '1']
        # ['1', '1', '1', '2', '2']
        # ['1', '0', '0', '1', '0']

        # ["1", "0", "1", "0", "0"]
        # ["1", "0", "1", "1", "1"]
        # ["1", "1", "1", "1", "1"]
        # ["1", "0", "0", "1", "0"]
        
        # ["1", "1", "1", "1"]
        # ["1", "1", "1", "1"]
        # ["1", "1", "1", "1"]

        # ['1', '1', '1', '1']
        # ['1', '2', '2', '2']
        # ['1', '2', '4', '4']

        return max_square * max_square
        
25625