Linked List Cycle
Explore the fast and slow pointers method to identify cycles in linked lists. Learn to return true if a cycle exists and false if not by analyzing node connections. This lesson helps you efficiently detect cycles to solve common linked list problems in coding interviews.
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Statement
Given the head of a linked list, determine whether the list contains a cycle. A cycle exists if a node in the list can be revisited by continuously following the next pointers. Return TRUE if a cycle is present; otherwise, return FALSE.
Constraints:
Let n be the number of nodes in a linked list.
-
n -
Node.value
Examples
Understand the problem
Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:
Linked List Cycle
What is the output if the following linked list is given as an input?
TRUE
FALSE
Figure it out!
We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.
Try it yourself
Implement your solution in the following coding playground.
// The first input of the test case is an array of values representing a linked list.// The second input is the index where the tail connects to form a cycle (or −1 if there's no cycle).// This index is used only to construct the linked list and is not passed to the function.// Definition for a Linked List node// class ListNode {// constructor(val = 0, next = null) {// this.val = val;// this.next = next;// }// }import {ListNode} from './ds_v1/LinkedList.js';function detectCycle(head){// Replace this placeholder return statement with your codereturn false;}export {detectCycle};