#1557
Minimum Number of Vertices to Reach All Nodes
pupil · 420 · lc medium +25 · verified · 81.5% accepted · 3,862 likes · top 93%
Description
In a directed acyclic graph with n vertices (labeled 0 to n-1) and directed edges edges[i] = [fromi, toi], find the smallest set of vertices such that every node is reachable from at least one vertex in the set. A unique solution is guaranteed; return the vertices in any order.
Example 1:
Input: n = 6, edges = [[0,1],[0,2],[2,5],[3,4],[4,2]]
Output: [0,3]
Explanation: It'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].
Example 2:
Input: n = 5, edges = [[0,1],[2,1],[3,1],[1,4],[2,4]]
Output: [0,2,3]
Explanation: Notice that vertices 0, 3 and 2 are not reachable from any other node, so we must include them. Also any of these vertices can reach nodes 1 and 4.
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