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MergeTwoSortedLists.hpp
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MergeTwoSortedLists.hpp
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//Merge Two Sorted Lists
//
//Merge two sorted linked lists and return it as a new list.
//The new list should be made by splicing together the nodes of the first two lists.
#include "LinkList.hpp"
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
if (NULL == l1 && NULL != l2)
return l2;
if (NULL == l2 && NULL != l1)
return l1;
if (NULL == l1 && NULL == l2)
return NULL;
ListNode* head = NULL;
ListNode* end = NULL;
while (NULL != l1 && NULL != l2)
{
if (l1->val <= l2->val)
{
if (NULL == head)
end = head = l1;
else
{
end->next = l1;
end = l1;
}
l1 = l1->next;
}
else
{
if (NULL == head)
end = head = l2;
else
{
end->next = l2;
end = l2;
}
l2 = l2->next;
}
}
if (NULL != l1)
{
end->next = l1;
end = end->next;
}
if (NULL != l2)
{
end->next = l2;
end = end->next;
}
while (NULL != end->next)
end = end->next;
end->next = NULL;
return head;
}
};