Leetcode-DSA-Solutions/MergeTwoSortedLists.cpp at main · smshozab/Leetcode-DSA-Solutions · GitHub

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/** * 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* list1, ListNode* list2) {
       if (list1 == nullptr) {
           return list2;
       }
       if (list2 == nullptr) {
           return list1;
       }
       ListNode* dummy = new ListNode(-1);
       ListNode* current = dummy;
       while (list1 != nullptr && list2 != nullptr) {
           if (list1->val < list2->val) {
               current->next = list1;
               list1 = list1->next;
           } else {
               current->next = list2;
               list2 = list2->next;
           }
           current = current->next;
       }
       if (list1 != nullptr) {
           current->next = list1;
       }
       if (list2 != nullptr) {
           current->next = list2;
       }
       ListNode* mergedList = dummy->next;
       delete dummy;
               return mergedList;
     }};