【leetcode】【单链表】【206】Reverse Linked List

#include<iostream>
#include<stack>
using namespace std;

struct ListNode {     
	int val;
	ListNode *next;
	ListNode(int x) : val(x), next(NULL) {}
};

class Solution {
public:
	/*ListNode* reverseList(ListNode* head) { //版本一
		ListNode* cur = head;
		ListNode* new_head = NULL;
		while (cur){
			ListNode* temp = cur;
			cur = cur->next;
			temp->next = new_head;
			new_head = temp;
		}
		head = new_head;
		return head;
	}*/
	ListNode* reverseList(ListNode* head) {<span style="font-family: Arial, Helvetica, sans-serif;">//版本二，用栈模拟</span>
		if (head == NULL || head->next == NULL)
			return head;

		stack<ListNode*> stk;
		while (head){
			stk.push(head);
			head = head->next;
		}
		head = stk.top();
		stk.pop();
		ListNode* cur = head;
		ListNode* temp = NULL;
		while (!stk.empty()){
			temp = stk.top();
			stk.pop();
			cur->next = temp;
			cur = temp;;
		}
		cur->next = NULL;

		return 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(){
	ListNode* head=NULL;
	Solution solution;
	head = solution.createList(head);
	solution.printNode(head);

	head = solution.reverseList(head);
	solution.printNode(head);

	system("pause");
	return 0;
}