merge-two-sorted-lists.java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        
        
        if(l1 == null) return l2;
        if(l2 == null) return l1;
        
        
        if(l1.val < l2.val){
            l1.next = mergeTwoLists(l1.next,l2);
            return l1;
        }
        else{
             
            l2.next = mergeTwoLists(l1,l2.next);
            return l2;
        }
    }
}