Daily-Problems-LeetCode/21.MergeTwoSortedLists.cpp at main · frostbyte012/Daily-Problems-LeetCode · GitHub

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#include <bits/stdc++.h>
using namespace std;


class Solution {


public:

    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) {}
 };


    ListNode* mergeTwoLists(ListNode* list1, ListNode* list2) {

     if(!list1)
     {
         return list2;
     }

     if(!list2)
     {
         return list1;
     }

     ListNode *temp,*head=list1;

     if(list1->val<list2->val)
     {
         list1=list1->next;
     }


     else{

        head=list2;

        list2=list2->next;


     }

    temp=head;

    while(list1&&list2)
    {
        if(list1->val<list2->val)
        {
            temp->next=list1;

            list1=list1->next;
        }
        else{

            temp->next=list2;

            list2=list2->next;
        }

        temp=temp->next;

    }

    if(!list1)
    {
        temp->next=list2;
    }


    if(!list2){
        temp->next=list1;
    }


    return head;

    }
};