<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:
    unordered_set<int>printed,printing;
    unordered_set<int>border;
    unordered_map<int,vector<int>>mp;
    bool dfs(int color,vector<vector<int>>&grid){
        if(printed.find(color)!=printed.end())return true;
        if(printing.find(color)!=printing.end())return false;

        for(int i=mp[color][0];i<mp[color][1]+1;i++){
            for(int j=mp[color][2];j<mp[color][3]+1;j++){
                if(grid[i][j]!=color){
                    printing.insert(color);
                    if(!dfs(grid[i][j],grid))return false;
                    printing.erase(color);
                }
            }
        }
        printed.insert(color);
        return true;
    }
    bool isPrintable(vector<vector<int>>&grid) {
        int n=grid.size(),m=grid[0].size();
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                int c=grid[i][j];
                border.insert(c);//saare unique cols miljyenge
                auto &v=mp[c];
                if(v.empty()){
                    v={i,i,j,j};
                }else{
                    //isse ye miljyega ki kitna cover hora hai kisi type ke color se
                    v[0]=min(v[0],i);//l
                    v[1]=max(v[1],i);//r
                    v[2]=min(v[2],j);//t
                    v[3]=max(v[3],j);//b
                }
            }
        }
        for(auto c:border){
            if(dfs(c,grid)==false)return false;
        }
        return true;
    }
};
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