【leetcode】【单链表】【148】Sort List

#include<iostream>using namespace std;struct ListNode {int val;ListNode *next;ListNode(int x) : val(x), next(NULL) {}};class Solution {public:ListNode* merge(ListNode* l1, ListNode* l2){ListNode* temp = new ListNode(0);ListNode* cur = temp;while (l1&&l2){if (l1->val < l2->val){cur->next = l1;l1 = l1->next;}else{cur->next = l2;l2 = l2->next;}cur = cur->next;}if (l1)cur->next = l1;elsecur->next = l2;cur = temp->next;temp->next = NULL;delete temp;return cur;}ListNode* mergeSort(ListNode* head){ //归并排序if (head == NULL || head->next == NULL)return head;ListNode* slow = head;ListNode* fast = head;ListNode* preSlow = NULL;while (fast&&fast->next){preSlow = slow;slow = slow->next;fast = fast->next->next;}preSlow->next = NULL;ListNode* lList = mergeSort(head);ListNode* rList = mergeSort(slow);return merge(lList, rList);}ListNode* sortList(ListNode* head) {if (head == NULL || head->next == NULL)return head;return mergeSort(head);}ListNode* createList(ListNode* head){int numOfNode;int value;cout << "please input number of listNode:";cin >> numOfNode;cin >> value;head = new ListNode(value);ListNode* cur = head;for (int i = 1; i < numOfNode; ++i){cin >> value;ListNode* temp = new ListNode(value);cur->next = temp;cur = temp;}return head;}void printNode(ListNode* head){ListNode* cur = head;while (cur){cout << cur->val << " ";cur = cur->next;}cout << endl;}};int main(){Solution solution;ListNode* head = NULL;head = solution.createList(head);solution.printNode(head);head = solution.sortList(head);solution.printNode(head);system("pause");return 0;}