GFG Split Circular Linked List into Two Halves

Problem Statement

Split a Circular Linked List into two halves | Practice | GeeksforGeeks

Pattern:

---

Solution

public void splitList (ListNode head){
	ListNode fast = head, slow = head;
	
	while(fast.next!= head && fast.next.next != head) {
		fast = fast.next.next;
		slow = slow.next;
	}
	// slow now points to mid
	
	// in case there's even no. of els in list
	while(fast.next != head) fast = fast.next;
	// fast now points to tail
	
	ListNode mid = slow, tail = fast, head2 = mid.next;
	
	// make both circular
	mid.next = head;
	tail.next = head2;
}

Notes

• Circular linked list are in a way not circular at all, since you know then end, when curr.next == head
• Now just find 876. Middle of the Linked List and slow will point to floor of mid, and fast will point to tail if LL is Odd, if its even, while(fast.next != head) fast = fast.next should give u the tail
• connect both tails, to heads