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Solution: Start of LinkedList Cycle

Problem Statement

Given the head of a Singly LinkedList that contains a cycle, write a function to find the starting node of the cycle.

Solution

If we know the length of the LinkedList cycle, we can find the start of the cycle through the following steps:

  1. Take two pointers. Let’s call them pointer1 and pointer2.
  2. Initialize both pointers to point to the start of the LinkedList.
  3. We can find the length of the LinkedList cycle using the approach discussed in LinkedList Cycle. Let’s assume that the length of the cycle is ‘K’ nodes.
  4. Move ``pointer2`

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sharmilasiram

· 2 years ago


#class Node:
#  def __init__(self, value, next=None):
#    self.val = value
#    self.next = next

class Solution:
  def findCycleStart(self, head):
    #TODO Write your code here
    if head == None or head.next == None:
      return None
    slow, fast = head, head
    while fast != None and fast.next != None:
      slow = slow.next
      fast = fast.next.next
      if slow == fast:
        slow = head 
        while slow != fast:
          slow = slow.next
          fast = fast.next
        return slow
    return None

I feel like if you don't refine this code, this course is not even worth the money I am paying

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