Problem Statement

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

class ListNode {
  int value = 0;
  ListNode next;
  ListNode(int value) {
    this.value = value;
  }
}
class LinkedListCycleStart {
  public static ListNode findCycleStart(ListNode head) {
    // TODO: Write your code here
    return head;
  }
  public static void main(String[] args) {
    ListNode head = new ListNode(1);
    head.next = new ListNode(2);
    head.next.next = new ListNode(3);
    head.next.next.next = new ListNode(4);
    head.next.next.next.next = new ListNode(5);
    head.next.next.next.next.next = new ListNode(6);
    head.next.next.next.next.next.next = head.next.next;
    System.out.println("LinkedList cycle start: " + LinkedListCycleStart.findCycleStart(head).value);
    head.next.next.next.next.next.next = head.next.next.next;
    System.out.println("LinkedList cycle start: " + LinkedListCycleStart.findCycleStart(head).value);
    head.next.next.next.next.next.next = head;
    System.out.println("LinkedList cycle start: " + LinkedListCycleStart.findCycleStart(head).value);
  }
}

Introduction

Pattern: Sliding Window

Pattern: Two Pointers

Pattern: Fast and Slow Patterns

Pattern: Merge Intervals

Pattern: Cyclic Sort

Pattern: In-place Reversal of a LinkedList

Pattern: Tree Breadth First Search

Pattern: Tree Depth First Search

Pattern: Two Heaps

Pattern: Subsets

Pattern: Modified Binary Search

Pattern: Bitwise XOR

Pattern: Top 'K' Elements

Pattern: K-way merge

Pattern : 0/1 Knapsack (Dynamic Programming)

Pattern: Topological Sort (Graph)

Miscellaneous

Conclusions

Start of LinkedList Cycle (medium)

Problem Statement

Try it yourself

Solution