<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 isPrintable(vector<vector<int>>& grid) {
        vector<vector<int>>graph(61,vector<int>(4,-1));//xl,xr,yl,yr
        vector<int>indegree;
        int n=grid.size(),m=grid[0].size(),maxi=0;

        for(int i=0;i< n;i++){
            for(int j=0;j< m;j++){
                int col=grid[i][j];
                if(graph[col][0]==-1){
                    graph[col][0]=i;
                    graph[col][1]=i;
                    graph[col][2]=j;
                    graph[col][3]=j;
                }else{
                    graph[col][0]=min(graph[col][0],i);
                    graph[col][1]=max(graph[col][1],i);
                    graph[col][2]=min(graph[col][2],j);
                    graph[col][3]=max(graph[col][3],j);
                }
                //cout<<col<<" "<<graph[col][0]<<" "<<graph[col][2]<<" "<<graph[col][1]<<" "<<graph[col][3]<< endl;

                maxi=max(maxi,grid[i][j]);
            }
        }
        indegree.resize(61,0);
        vector<int>adj[61];
        cout<< maxi<<" "<< endl;

        for(int col=1;col<= maxi;col++){
            if(graph[col][0]==-1)
            continue;
            //cout<<col<<" "<<graph[col][0]<<" "<<graph[col][2]<<" "<<graph[col][1]<<" "<<graph[col][3]<< endl;
            for(int i= graph[col][0];i<=graph[col][1];i++){
                 for(int j= graph[col][2];j<=graph[col][3];j++){
                      if(grid[i][j]!=col){
                        adj[col].push_back(grid[i][j]);
                        indegree[grid[i][j]]++;
                        //cout<< col<<" "<<grid[i][j]<< endl;
                      int nc=grid[i][j];
                      if(grid[i][j]!=col && graph[col][0]==graph[nc][0] &&
                      graph[col][1]==graph[nc][1] && graph[col][2]==graph[nc][2] &&
                      graph[col][3]==graph[nc][3])
                      return 0;
                      }
                 }
            }
        }

        queue<int>q;
        for(int i=1;i<=maxi;i++){
            if(indegree[i]==0)
            q.push(i);
            //cout<< i<<" "<<indegree[i]<< endl;
        }
        while(q.empty()==false){
            int node=q.front();
            q.pop();
            for(auto j:adj[node]){
                indegree[j]--;
                if(indegree[j]==0)
                q.push(j);
            }
        }
        for(int i=1;i<= maxi;i++){
            if(indegree[i]!=0)
            return 0;
        }
        return 1;
    }
};
20858