[LeetCode] Linked List Cycle

문제

Given a linked list, determine if it has a cycle in it.

To represent a cycle in the given linked list, we use an integer pos which represents the position (0-indexed) in the linked list where tail connects to. If pos is -1, then there is no cycle in the linked list.

 

Example 1:

Input: head = [3,2,0,-4], pos = 1 Output: true Explanation: There is a cycle in the linked list, where tail connects to the second node.

Example 2:

Input: head = [1,2], pos = 0 Output: true Explanation: There is a cycle in the linked list, where tail connects to the first node.

Example 3:

Input: head = [1], pos = -1 Output: false Explanation: There is no cycle in the linked list.

Approach

두 개의 포인터를 선언하고

하나는 두 칸씩, 하나는 한 칸씩 이동하도록 한다.

포인터가 NULL 이되면 싸이클이 없는 것이고

싸이클이 있다면 두 포인터가 같게 되는 순간이 온다.

 

Code

https://github.com/chi3236/algorithm/blob/master/LeetCode_Linked_List_Cycle.cpp

chi3236/algorithm