Grokking Data Structures & Algorithms for Coding Interviews
Vote

0% completed

​

Solution: Swap Nodes in Pairs

.....

.....

.....

Like the course? Get enrolled and start learning!
A

Anonymous

· 2 years ago

In this solution I swapped the values instead of the references which is simpler , It may not be the correct approach to get familiar with LinkedList

Solution {

	public ListNode swapPairs(ListNode head) {
		// TODO: Write your code hereu
		ListNode current = head;
		while(current != null && current.next != null) {
			int t = current.val;
			current.val = current.next.val;
			current.next.val = t;
			current = current.next.next;
		}
		return head;
	}
}
A

Anonymous

· 2 years ago

// class ListNode {
//     int val;
//     ListNode next;
//     ListNode() {}
//     ListNode(int val) { this.val = val; }
//     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
// }

class Solution {
    public ListNode swapPairs(ListNode head) {
        ListNode p =  head;
        ListNode dummy = new ListNode(-1);
        ListNode t = dummy;
        ListNode prev = head;
    
        for (int i = 0; p != null; i++, prev = p, p = p.next) {
            if (i % 2 != 0) {
                t.next = new ListNode(p.val);
                t = t.next;
                t.next = new ListNode(prev.val);
                t = t.next;
            } else if (p.next == null) {
               t.next = new ListNode(p.val);
               t = t.next; 
            }
Show 1 reply
A

Anonymous

· 3 years ago

public ListNode swapPairs(ListNode head) {
        if(head == null || head.Next == null)
        return head;

        var temp = head.Next;
        head.Next = swapPairs(head.Next.Next);
        temp.Next = head;

        return temp;
    
    }

Reading Progress

0%

Vote for new content