Merge Two Sorted Lists

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

Merge the two lists in a 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.

Solution:

Language:Java

/**
 * Definition for singly-linked list.
 * public 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 mergeTwoLists(ListNode list1, ListNode list2) 
    {
      ListNode temp = new ListNode() ;
      ListNode tail = temp ;

      while(list1!=null && list2!=null)
      {
          if(list1.val < list2.val)
          {
              tail.next=list1 ;
              list1=list1.next;
              tail=tail.next;

          }
          else
          {
              tail.next=list2;
              list2=list2.next;
              tail=tail.next;
          }
      }

      tail.next=(list1!=null)?list1:list2;
      return temp.next ;

    }
}