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

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#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;}

参考：http://blog.sina.com.cn/s/blog_725dd1010100tqwp.html

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