public class Solution
extends Object
1557 - Minimum Number of Vertices to Reach All Nodes\.
Medium
Given a** directed acyclic graph** , with `n` vertices numbered from `0` to `n-1`, and an array `edges` where edges[i] = [fromi, toi] represents a directed edge from node fromi to node toi.
Find _the smallest set of vertices from which all nodes in the graph are reachable_. It's guaranteed that a unique solution exists.
Notice that you can 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.
**Constraints:**
* `2 <= n <= 10^5`
* `1 <= edges.length <= min(10^5, n * (n - 1) / 2)`
* `edges[i].length == 2`
* 0 <= fromi, toi < n
* All pairs (fromi, toi) are distinct.