<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:

    vector<int> topoSort(int V, vector<int> adj[],set<int>&st)
	{
		//int indegree[V+3] = {0};
        vector<int>indegree(V+3,0);
		for (int i =1 ; i < V; i++) {
             if(st.find(i)==st.end()) continue;
			for (auto it : adj[i]) {
				indegree[it]++;
			}
		}

		queue<int> q;
		for (int i = 1; i < V; i++) {
             if(st.find(i)==st.end()) continue;
			if (indegree[i] == 0) {
				q.push(i);
			}
		}
		vector<int> topo;
		while (!q.empty()) {
			int node = q.front();
			q.pop();
			topo.push_back(node);
			// node is in your topo sort
			// so please remove it from the indegree

			for (auto it : adj[node]) {
				indegree[it]--;
				if (indegree[it] == 0) q.push(it);
			}
		}

		return topo;
	}
    bool isPrintable(vector<vector<int>>& targetGrid) {
        int n = targetGrid.size();
        int m = targetGrid[0].size();

        vector<vector<int>> v(61, vector<int>(4));
        for (int i = 0; i < 61; i++) {
            v[i][0] = INT_MAX;
            v[i][1] = INT_MIN;
            v[i][2] = INT_MAX;
            v[i][3] = INT_MIN;
        }
              set<int>st;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                st.insert(targetGrid[i][j]);
                v[targetGrid[i][j]][0] = min(i, v[targetGrid[i][j]][0]);
                v[targetGrid[i][j]][1] = max(i, v[targetGrid[i][j]][1]);
                v[targetGrid[i][j]][2] = min(j, v[targetGrid[i][j]][2]);
                v[targetGrid[i][j]][3] = max(j, v[targetGrid[i][j]][3]);
            }
        }

        vector<int> adj[61];

        for (int i = 1; i <= 60; i++) {
            if(st.find(i)==st.end()) continue;
            for (int j = 0; j < n; j++) {
                for (int k = 0; k < m; k++) {
                    if (v[i][0] <= j && j <= v[i][1] && v[i][2] <= k &&
                        k <= v[i][3]) {
                        if (targetGrid[j][k] != i)
                            adj[i].push_back(targetGrid[j][k]);
                    }
                }
            }
        }

       return (topoSort(61,adj,st).size() == st.size()) ? true :false;
    }
};
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