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Kotlin-based LeetCode algorithm problem solutions, regularly updated
2360\. Longest Cycle in a Graph
Hard
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:**
![](https://assets.leetcode.com/uploads/2022/06/08/graph4drawio-5.png)
**Input:** edges = [3,3,4,2,3]
**Output:** 3
**Explanation:** The longest cycle in the graph is the cycle: 2 -> 4 -> 3 -> 2.
The length of this cycle is 3, so 3 is returned.
**Example 2:**
![](https://assets.leetcode.com/uploads/2022/06/07/graph4drawio-1.png)
**Input:** edges = [2,-1,3,1]
**Output:** -1
**Explanation:** There are no cycles in this graph.
**Constraints:**
* `n == edges.length`
* 2 <= n <= 105
* `-1 <= edges[i] < n`
* `edges[i] != i`