Package g0801_0900.s0802_find_eventual_safe_states

Class Solution

  • public class Solution
extends Object
    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.

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

    Example 1:

    Illustration of graph

    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
    • 1 <= n <= 104
    • 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 [1, 4 * 104].

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • eventualSafeNodes

        public List<Integer> eventualSafeNodes​(int[][] graph)