Longest Cycle in a Graph
You are given a directed graph of n nodes numbered from 0 to n - 1, where each node has at most one outgoing edge.
The graph is represented with a given 0-indexed array edges of size n, indicating that there is a directed edge from node i to node edges[i]. If there is no outgoing edge from node i, then edges[i] == -1.
Return the length of the longest cycle in the graph. If no cycle exists, return -1.
A cycle is a path that starts and ends at the same node.
Example 1
Input
edges = [3,3,4,2,3]Output
3The longest cycle in the graph is 2 -> 4 -> 3 -> 2, whose length is 3.
Example 2
Input
edges = [2,-1,3,1]Output
-1There are no cycles in this graph.
Constraints
- n == edges.length
- 2 <= n <= 10^5
- -1 <= edges[i] < n
- edges[i] != i