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How to Solve Longest Cycle in a Graph Problem
Master the Longest Cycle in a Graph LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.
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Start Free for WindowsHard#2360
LeetCode ProblemLongest 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.
Depth-First SearchBreadth-First SearchGraphTopological Sort
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Problem Breakdown
Understanding the Longest Cycle in a Graph Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
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.
HardProblem #2360
LeetCodeLongest Cycle in a Graph
Related Topics
Depth-First SearchBreadth-First SearchGraphTopological Sort
How Phantom Code Helps
Get real-time assistance for Longest Cycle in a Graph problems during coding interviews. Phantom Code provides instant solutions and explanations.
Examples
# Example 1
Input
edges = [3,3,4,2,3]
Output
3
# Example 2
Input
edges = [2,-1,3,1]
Output
-1
Constraints
n == edges.length
2 <= n <= 105
-1 <= edges[i] < n
edges[i] != i
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Solve Longest Cycle in a Graph — You are given a directed graph of n nodes numbered from 0 to n - 1, where each n...
Here's the optimal approach using Depth-First Search:
def solve(input):
# Optimal O(n) solution
return result
Time: O(n) | Space: O(n)
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HackerRank
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Frequently Asked Questions
Common questions about solving Longest Cycle in a Graph and using Phantom Code during coding interviews.
How does Phantom Code help me solve coding problems like Longest Cycle in a Graph during interviews?
Phantom Code generates complete solutions instantly with proper complexity analysis, letting you focus on explaining your approach and demonstrating problem-solving skills rather than getting stuck on implementation details during high-pressure situations.
What if the interviewer asks follow-up questions or modifications to problems like Longest Cycle in a Graph?
Phantom Code adapts in real-time. Screenshot the modified problem or use audio mode to capture the interviewer's follow-up, and get an updated solution within seconds — including edge cases and optimizations.
Can Phantom Code help me communicate my solution for problems like Longest Cycle in a Graph?
Yes. Phantom Code provides step-by-step approach explanations with 3 progressive thoughts, so you can walk through your solution naturally. It also provides time and space complexity analysis to discuss trade-offs.
How does Phantom Code assist with different programming languages for Longest Cycle in a Graph type problems?
Phantom Code supports 11 programming languages including Python, Java, C++, JavaScript, TypeScript, Go, Rust, Ruby, Swift, Kotlin, and C#. Set your preferred language and get idiomatic solutions.
What coding mistakes does Phantom Code help me avoid during Longest Cycle in a Graph interviews?
Phantom Code catches common mistakes like off-by-one errors, missing edge cases, incorrect base conditions, and suboptimal approaches. It provides clean, well-structured code that handles all edge cases.
Is Phantom Code detectable when solving problems like Longest Cycle in a Graph during live interviews?
No. Phantom Code runs as an invisible desktop overlay that doesn't appear in screen shares, recordings, or proctoring software. It works with Zoom, HackerRank, CodeSignal, CoderPad, and all major platforms.
How does Phantom Code help when I'm struggling with Longest Cycle in a Graph style questions under pressure?
The AI provides structured guidance: first the approach (what algorithm/data structure to use and why), then the implementation with clean code, and finally complexity analysis. This helps you think clearly even under pressure.
Does Phantom Code work for the coding platforms used in Longest Cycle in a Graph interviews?
Yes. Phantom Code works with all major coding platforms including LeetCode, HackerRank, CodeSignal, CoderPad, HackerEarth, and any browser-based coding environment.
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