【leetcode】【141】Linked List Cycle

#include<iostream>
using namespace std;

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

class Solution {
public:
bool hasCycle(ListNode *head) {
if (head == NULL || head->next == NULL) //链表空或只有一个节点
return false;

ListNode* slow = head;
ListNode* fast = head;
while (fast&&fast->next){
slow = slow->next;
fast = fast->next->next;
if (slow == fast)
return true;
}
return false;
}
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;
}
//cur->next = head;
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 lst;
head = lst.createList(head);
//lst.printNode(head);

cout << boolalpha << lst.hasCycle(head) << endl;

system("pause");
return 0;
}