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Leetcode148.cpp
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96 lines (83 loc) · 2.64 KB
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// Leetcode148.cpp : This file contains the 'main' function. Program execution begins and ends there.
//
#include <iostream>
/**
* 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* sortList(ListNode* head) {
if (head == nullptr || head->next == nullptr)
return head;
ListNode* temp = nullptr;
ListNode* slow = head;
ListNode* fast = head;
while (fast != nullptr && fast->next != nullptr)
{
temp = slow;
slow = slow->next;
fast = fast->next->next;
}
temp->next = nullptr;
ListNode* list1 = sortList(head);
ListNode* list2 = sortList(slow);
return merge(list1, list2);
}
ListNode* merge(ListNode* list1, ListNode* list2)
{
ListNode* realHead = nullptr;
ListNode* tail = nullptr;
while (list1 != nullptr && list2 != nullptr)
{
if (list1->val < list2->val)
{
if (realHead == nullptr)
{
realHead = tail = list1;
}
else
{
tail->next = list1;
tail = tail->next;
}
list1 = list1->next;
}
else
{
if (realHead == nullptr)
{
realHead = tail = list2;
}
else
{
tail->next = list2;
tail = tail->next;
}
list2 = list2->next;
}
}
if (list1 != nullptr) tail->next = list1;
if (list2 != nullptr) tail->next = list2;
return realHead;
}
};
int main()
{
std::cout << "Hello World!\n";
}
// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu
// Tips for Getting Started:
// 1. Use the Solution Explorer window to add/manage files
// 2. Use the Team Explorer window to connect to source control
// 3. Use the Output window to see build output and other messages
// 4. Use the Error List window to view errors
// 5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
// 6. In the future, to open this project again, go to File > Open > Project and select the .sln file