【leetcode】【单链表】【142】Linked List Cycle II

#include<iostream>
using namespace std;

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

class Solution {
public:
ListNode *detectCycle(ListNode *head) {
ListNode* slow = head;
ListNode* fast = head;
while (fast&&fast->next){
slow = slow->next;
fast = fast->next->next;
if (slow == fast){
ListNode* cur = head;
while (cur != slow){
cur = cur->next;
slow = slow->next;
}
return cur;
}
}
return NULL;
}
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->next;
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);

cout << solution.detectCycle(head)->val << endl;

system("pause");
return 0;
}