<p>There is a strange printer with the following two special requirements:</p>

<ul>
	<li>On each turn, the printer will print a solid rectangular pattern of a single color on the grid. This will cover up the existing colors in the rectangle.</li>
	<li>Once the printer has used a color for the above operation, <strong>the same color cannot be used again</strong>.</li>
</ul>

<p>You are given a <code>m x n</code> matrix <code>targetGrid</code>, where <code>targetGrid[row][col]</code> is the color in the position <code>(row, col)</code> of the grid.</p>

<p>Return <code>true</code><em> if it is possible to print the matrix </em><code>targetGrid</code><em>,</em><em> otherwise, return </em><code>false</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/12/23/print1.jpg" style="width: 600px; height: 175px;" />
<pre>
<strong>Input:</strong> targetGrid = [[1,1,1,1],[1,2,2,1],[1,2,2,1],[1,1,1,1]]
<strong>Output:</strong> true
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/12/23/print2.jpg" style="width: 600px; height: 367px;" />
<pre>
<strong>Input:</strong> targetGrid = [[1,1,1,1],[1,1,3,3],[1,1,3,4],[5,5,1,4]]
<strong>Output:</strong> true
</pre>

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

<pre>
<strong>Input:</strong> targetGrid = [[1,2,1],[2,1,2],[1,2,1]]
<strong>Output:</strong> false
<strong>Explanation:</strong> It is impossible to form targetGrid because it is not allowed to print the same color in different turns.
</pre>

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

<ul>
	<li><code>m == targetGrid.length</code></li>
	<li><code>n == targetGrid[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 60</code></li>
	<li><code>1 &lt;= targetGrid[row][col] &lt;= 60</code></li>
</ul>

class Solution:
    def isPrintable(self, targetGrid: List[List[int]]) -> bool:
        m, n = len(targetGrid), len(targetGrid[0])
        color_set = set(sum(targetGrid, []))
        color_rect = {color: [m, n, 0, 0] for color in color_set}
        
        for i in range(m):
            for j in range(n):
                color = targetGrid[i][j]
                x1, y1, x2, y2 = color_rect[color]
                color_rect[color] = [min(x1, i), min(y1, j), max(x2, i), max(y2, j)]
        
        graph = {color: set() for color in color_set}
        for color in color_set:
            x1, y1, x2, y2 = color_rect[color]
            for i in range(x1, x2 + 1):
                for j in range(y1, y2 + 1):
                    if targetGrid[i][j] != color:
                        graph[color].add(targetGrid[i][j])
        
        def has_cycle(color, visited, stack):
            visited.add(color)
            stack.add(color)
            for next_color in graph[color]:
                if next_color not in visited:
                    if has_cycle(next_color, visited, stack):
                        return True
                elif next_color in stack:
                    return True
            stack.remove(color)
            return False
        
        visited = set()
        for color in color_set:
            if color not in visited:
                if has_cycle(color, visited, set()):
                    return False
        return True
18000