PRoblem

Insert a node in a sorted linked list.

Example

Given list = 1->4->6->8 and val = 5.

Return 1->4->5->6->8.

Solution

public class Solution {
    public ListNode insertNode(ListNode head, int val) {
        
        ListNode dummy = new ListNode(0);
        dummy.next = head;
        ListNode node = new ListNode(val);
        
        //if val is the smallest in entire list
        if (head == null || val < head.val) {
            dummy.next = node;
            node.next = head;
            return dummy.next;
        }
        
        //while val is larger than head.val, loop the linked list and check the range between head & head.next to insert
        while (head != null && head.next != null) {
            if (head.val <= val && val <= head.next.val) {
                ListNode next = head.next;
                head.next = node;
                node.next = next;
                break;
            } else if (val > head.next.val) {
                head = head.next;
            }
        }
        
        //if node not inserted in the loop
        if (head.next == null) {
            head.next = node;
        }

        return dummy.next;
    }
}