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 <code>edgesi = from_i, to_i</code> represents a directed edge from node <code>from_i</code> to node <code>to_i</code>.

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

• <code>0 <= from_i, to_i< n</code>

• All pairs <code>(from_i, to_i)</code> are distinct.