Last updated on February 22nd, 2024 at 03:24 am

Here, We see Merge Two Sorted Lists LeetCode Solution. This Leetcode problem is done in many programming languages like C++, Java, JavaScript, Python, etc. with a different approach.

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Merge Two Sorted Lists LeetCode Solution

Problem Statement

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: (fig-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]

Merge Two Sorted Lists Leetcode Solution C++

class Solution {
public:
    ListNode* mergeTwoLists(ListNode* list1, ListNode* list2) {
        if(list1 == NULL) return list2;
        if(list2 == NULL) return list1;
        if(list1->val>=list2->val) list2->next = mergeTwoLists(list1, list2-> next);
        else{
            list1->next = mergeTwoLists(list1->next, list2);
            list2 = list1;
        }return list2;
    }
};
Code language: C++ (cpp)

Merge Two Sorted Lists Leetcode Solution Java

class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
		if(list1 == null) return list2;
		if(list2 == null) return list1;
		if(list1.val < list2.val){
			list1.next = mergeTwoLists(list1.next, list2);
			return list1;
		} else{
			list2.next = mergeTwoLists(list1, list2.next);
			return list2;        
    }
    }
}
Code language: Java (java)

Merge Two Sorted Lists Leetcode Solution JavaScript

var mergeTwoLists = function(list1, list2) {
    var mergedHead = { val : -1, next : null },
        crt = mergedHead;
    while(list1 && list2) {
        if(list1.val > list2.val) {
            crt.next = list2;
            list2 = list2.next;
        } else {
            crt.next = list1;
            list1 = list1.next;
        }
        crt = crt.next;
    }
    crt.next = list1 || list2;
    
    return mergedHead.next;    
};
Code language: JavaScript (javascript)

Merge Two Sorted Lists Leetcode Solution Python

class Solution(object):
    def mergeTwoLists(self, list1, list2):
        dummy = cur = ListNode(0)
        while list1 and list2:
            if list1.val < list2.val:
                cur.next = list1
                list1 = list1.next
            else:
                cur.next = list2
                list2 = list2.next
            cur = cur.next
        cur.next = list1 or list2
        return dummy.next
Code language: Python (python)