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]
class Solution {
public:
ListNode* mergeTwoLists(ListNode* list1, ListNode* list2) {
if(list1 == NULL)
return list2;
if(list2 == NULL)
return list1;
ListNode * ptr = list1;
if(list1 -> val > list2 -> val)
{
ptr = list2;
list2 = list2 -> next;
}
else
{
list1 = list1 -> next;
}
ListNode *curr = ptr;
while(list1 && list2)
{
if(list1 -> val < list2 -> val){
curr->next = list1;
list1 = list1 -> next;
}
else{
curr->next = list2;
list2 = list2 -> next;
}
curr = curr -> next;
}
if(!list1)
curr -> next = list2;
else
curr -> next = list1;
return ptr;
}
};
