<p>You are given a <strong>directed</strong> graph of <code>n</code> nodes numbered from <code>0</code> to <code>n - 1</code>, where each node has <strong>at most one</strong> outgoing edge.</p>

<p>The graph is represented with a given <strong>0-indexed</strong> array <code>edges</code> of size <code>n</code>, indicating that there is a directed edge from node <code>i</code> to node <code>edges[i]</code>. If there is no outgoing edge from node <code>i</code>, then <code>edges[i] == -1</code>.</p>

<p>Return <em>the length of the <strong>longest</strong> cycle in the graph</em>. If no cycle exists, return <code>-1</code>.</p>

<p>A cycle is a path that starts and ends at the <strong>same</strong> node.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2022/06/08/graph4drawio-5.png" style="width: 335px; height: 191px;" />
<pre>
<strong>Input:</strong> edges = [3,3,4,2,3]
<strong>Output:</strong> 3
<strong>Explanation:</strong> The longest cycle in the graph is the cycle: 2 -&gt; 4 -&gt; 3 -&gt; 2.
The length of this cycle is 3, so 3 is returned.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2022/06/07/graph4drawio-1.png" style="width: 171px; height: 161px;" />
<pre>
<strong>Input:</strong> edges = [2,-1,3,1]
<strong>Output:</strong> -1
<strong>Explanation:</strong> There are no cycles in this graph.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>n == edges.length</code></li>
	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
	<li><code>-1 &lt;= edges[i] &lt; n</code></li>
	<li><code>edges[i] != i</code></li>
</ul>

class Solution:
    # def longestCycle(self, edges: List[int]) -> int:
    #     def dfs(i,edges,visit):
    #         stack=[]
    #         stack.append(i)
    #         n=0
    #         while stack:
    #             ele=stack.pop()
    #             visit.append(ele)
    #             next=edges[ele]
    #             if next!=-1 and next not in visit:
    #                 stack.append(next)
    #                 n+=1
    #             elif next == -1:
    #                 return -1
    #             elif next in visit:
    #                 return n
    #         return -1
    #     nodes=-1
    #     visit=[]

    #     for i in range(len(edges)):
    #         if edges[i]!=-1 and edges[i] not in visit:
    #             nodes=max(nodes,dfs(i,edges,visit))
    #     print(visit)

    #     return nodes
    def longestCycle(self, edges: List[int]) -> int:

        def dfs(v, edges, visited, visited_depth, depth=0):
            visited_depth[v] = depth
            visited.add(v)
            next_node = edges[v]
            if next_node != -1:
                if next_node in visited_depth:
                    return depth - visited_depth[next_node] + 1
                elif next_node not in visited:
                    length = dfs(next_node, edges, visited, visited_depth, depth + 1)
                    if length != -1:
                        return length

            return -1

        visited = set()
        max_value = -1

        for v in range(len(edges)):
            if edges[v]!=-1 and v not in visited:
                visited_depth = {}
                max_value = max(max_value, dfs(v, edges, visited, visited_depth))
        return max_value
61291