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leetcode/problem/minimum-number-of-vertices-to-reach-all-nodes.html

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+<p>Given a<strong>&nbsp;directed acyclic graph</strong>,&nbsp;with&nbsp;<code>n</code>&nbsp;vertices numbered from&nbsp;<code>0</code>&nbsp;to&nbsp;<code>n-1</code>,&nbsp;and an array&nbsp;<code>edges</code>&nbsp;where&nbsp;<code>edges[i] = [from<sub>i</sub>, to<sub>i</sub>]</code>&nbsp;represents a directed edge from node&nbsp;<code>from<sub>i</sub></code>&nbsp;to node&nbsp;<code>to<sub>i</sub></code>.</p>
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+
+
+<p>Find <em>the smallest set of vertices from which all nodes in the graph are reachable</em>. It&#39;s guaranteed that a unique solution exists.</p>
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+
+
+<p>Notice that you can return the vertices in any order.</p>
+
+
+
+<p>&nbsp;</p>
+
+<p><strong>Example 1:</strong></p>
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+
+
+<p><img alt="" src="https://assets.leetcode.com/uploads/2020/07/07/untitled22.png" style="width: 231px; height: 181px;" /></p>
+
+
+
+<pre>
+
+<strong>Input:</strong> n = 6, edges = [[0,1],[0,2],[2,5],[3,4],[4,2]]
+
+<strong>Output:</strong> [0,3]
+
+<b>Explanation: </b>It&#39;s not possible to reach all the nodes from a single vertex. From 0 we can reach [0,1,2,5]. From 3 we can reach [3,4,2,5]. So we output [0,3].</pre>
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+
+
+<p><strong>Example 2:</strong></p>
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+
+