<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(vector<vector<int>>&matrix, int col, vector<int> &vis) {
        if(vis[col] == -1) return true;
        if(vis[col] == 1) return false;

        int m = matrix.size(), n = matrix[0].size();
        int l = INT_MAX, r = INT_MIN, u = INT_MAX, d = INT_MIN;
        for(int i=0; i<m; i ++){
            for(int j=0; j<n; j++){
                if(matrix[i][j] == col){
                    l = min(l, j), r = max(r, j); 
                    u = min(u, i), d = max(d, i);
                }
            }
        }
        
        if(l == INT_MAX) return true;
        vis[col] = 1;
        
        for(int i=u; i<=d; i ++){
            for(int j=l; j<=r; j++){
                if(matrix[i][j] != col && !dfs(matrix, matrix[i][j], vis)){
                    return false;
                }
            }
        }
        
        vis[col] = -1;
        return true;
    }
    bool isPrintable(vector<vector<int>>& targetGrid) {
        int m = targetGrid.size(), n = targetGrid[0].size();
        vector<int> vis(61,0); 
        for(int col=1; col<61; col++){
            if(!dfs(targetGrid, col, vis)) return false; 
        }
        return true;
    }
};
16729