802 - Find Eventual Safe States.

Medium

There is a directed graph of n nodes with each node labeled from 0 to n - 1. The graph is represented by a 0-indexed 2D integer array graph where graph[i] is an integer array of nodes adjacent to node i, meaning there is an edge from node i to each node in graph[i].

A node is a terminal node if there are no outgoing edges. A node is a safe node if every possible path starting from that node leads to a terminal node (or another safe node).

Return an array containing all the safe nodes of the graph. The answer should be sorted in ascending order.

Example 1:

Input: graph = [1,2,2,3,5,0,5,[],[]]

Output: 2,4,5,6

Explanation: The given graph is shown above. Nodes 5 and 6 are terminal nodes as there are no outgoing edges from either of them. Every path starting at nodes 2, 4, 5, and 6 all lead to either node 5 or 6.

Example 2:

Input: graph = [1,2,3,4,1,2,3,4,0,4,[]]

Output: 4

Explanation: Only node 4 is a terminal node, and every path starting at node 4 leads to node 4.

Constraints:

• n == graph.length

• <code>1 <= n <= 10⁴</code>

• 0 <= graph[i].length <= n

• 0 <= graph[i][j] <= n - 1

• graph[i] is sorted in a strictly increasing order.

• The graph may contain self-loops.

• The number of edges in the graph will be in the range <code>1, 4 * 10⁴</code>.