Linked List.md

Linked List

Table of contents

• Floyd’s Cycle Detection Algorithm

Floyd’s Cycle Detection Algorithm

• Purpose: Detect if a linked list contains a cycle (loop) using two pointers — a slow one and a fast one.

• Working:

  • slow moves one node at a time.
  • fast moves two nodes at a time.
  • If there’s a cycle, both pointers will meet at some node inside the cycle.
  • If there's no cycle, fast will reach the end (null).

• Logic

public boolean hasCycle(ListNode head) {
        ListNode slow_p = head, fast_p = head;
        while(fast_p != null && fast_p.next != null) {
            slow_p = slow_p.next;
            fast_p = fast_p.next.next;
            if(slow_p == fast_p)return true;
        }
        return false;
    }

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