Merge Two Sorted Lists Leetcode Solution

In this post, we are going to solve the Merge Two Sorted Lists Leetcode Solution problem of Leetcode. This Leetcode problem is done in many programming languages like C++, Java, and Python.

Table of Contents

Problem

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.

Now, let’s see the leetcode solution of Merge Two Sorted Lists Leetcode Solution.

Merge Two Sorted Lists Leetcode Solution in Python

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
def mergeTwoLists1(self, l1, l2):
    dummy = cur = ListNode(0)
    while l1 and l2:
        if l1.val < l2.val:
            cur.next = l1
            l1 = l1.next
        else:
            cur.next = l2
            l2 = l2.next
        cur = cur.next
    cur.next = l1 or l2
    return dummy.next

Merge Two Sorted Lists Leetcode Solution in CPP

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
       ListNode* temp = new ListNode(-1);
        ListNode* head = temp;
        while(l1!=NULL and l2!=NULL){
            if(l1->val<=l2->val){
                head->next = l1;
                l1 = l1->next;
            }
            else {
                head->next = l2;
                l2 = l2->next;
            }
            head=head->next;
        }
        if(l1!=NULL)
        {
            head->next = l1;
        }
        else head->next = l2;
        
        return temp->next;
    }
};

Merge Two Sorted Lists Leetcode Solution in 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; }
 * }
 */
public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode head = new ListNode(0);
        ListNode handler = head;
        while(l1 != null && l2 != null) {
            if (l1.val <= l2.val) {
                handler.next = l1;
                l1 = l1.next;
            } else {
                handler.next = l2;
                l2 = l2.next;
            }
            handler = handler.next;
        }
        
        if (l1 != null) {
            handler.next = l1;
        } else if (l2 != null) {
            handler.next = l2;
        }
        
        return head.next;
    }
}

Note: This problem Merge Two Sorted Lists is generated by Leetcode but the solution is provided by Chase2learn This tutorial is only for Educational and Learning purposes.

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