cpp-programs/Merge Two Sorted Lists.cpp at main · gauravgupta654/cpp-programs · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
/**
 * 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) {
        ListNode* t1 = list1;
        ListNode* t2 = list2;
        ListNode* dummyNode = new ListNode(-1);
        ListNode* temp = dummyNode;

        while(t1 != NULL && t2 != NULL){
            if(t1 -> val < t2 -> val){
                temp->next = t1;
                temp = t1;
                t1 = t1->next;
            }
            else{
                temp->next = t2;
                temp = t2;
                t2 = t2->next;

            }
        }
        if(t1) temp->next =t1;
        else{
            temp->next = t2;
        }
        return dummyNode->next;
    }
};