Day 62 of 100 Days LeetCode Challenge

LeetCode Challenge #21. Merge Two Sorted Lists

You are given the heads of two sorted linked lists list1 and list2.

Merge the two lists into one sorted list. The list should be made by splicing together the nodes of the first two lists.

Return the head of the merged linked list.

 

Example 1:

Input: list1 = [1,2,4], list2 = [1,3,4]
Output: [1,1,2,3,4,4]

Example 2:

Input: list1 = [], list2 = []
Output: []

Example 3:

Input: list1 = [], list2 = [0]
Output: [0]

 

Constraints:

  • The number of nodes in both lists is in the range [0, 50].
  • -100 <= Node.val <= 100
  • Both list1 and list2 are sorted in non-decreasing order.
Video Solution
Java Solution
				
					class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        ListNode dummy = new ListNode(-1);
        ListNode ans = dummy ;
        ListNode ptr1 = list1;
        ListNode ptr2 = list2;

        while(ptr1!=null && ptr2!=null){
            if(ptr1.val<ptr2.val){
                dummy.next = ptr1 ;
                ptr1 = ptr1.next;    
            }else {
                dummy.next = ptr2 ;
                ptr2 = ptr2.next;  
            }

            dummy = dummy.next;
        }

        if(ptr1==null){
            dummy.next = ptr2;
        }else{
            dummy.next = ptr1 ;
        }

        return ans.next;
    }
}
				
			

Happy Coding with edSlash