<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 {
public:
    bool dfs(int col, unordered_set<int> overlaps[], vector<int>& vis) {
        if (vis[col] != 0)
            return vis[col] == 2;
        vis[col] = 1;
        for (auto col1 : overlaps[col])
            if (!dfs(col1, overlaps, vis))
                return false;
        vis[col] = 2;
        return true;
    }
    bool isPrintable(vector<vector<int>>& grid) {
        vector<array<int, 4>> rects(61, {INT_MAX, INT_MAX, INT_MIN, INT_MIN});
        unordered_set<int> overlaps[61];
        for (int i = 0; i < grid.size(); ++i)
            for (int j = 0; j < grid[0].size(); ++j) {
                int col = grid[i][j];
                rects[col][0] = min(rects[col][0], i);
                rects[col][1] = min(rects[col][1], j);
                rects[col][2] = max(rects[col][2], i);
                rects[col][3] = max(rects[col][3], j);
            }
        for (auto col = 0; col <= 60; ++col)
            for (int i = rects[col][0]; i <= rects[col][2]; ++i)
                for (int j = rects[col][1]; j <= rects[col][3]; ++j)
                    if (grid[i][j] != col)
                        overlaps[col].insert(grid[i][j]);
        for (auto col = 0; col <= 60; ++col)
            if (!dfs(col, overlaps, vector<int>(61) = {}))
                return false;
        return true;
    }
};
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