LeetCode对链表的一些操作题目

永兴呵呵哒

于 2019-07-24 19:34:29 发布

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分类专栏： C++学习

本文链接：https://blog.youkuaiyun.com/u014106566/article/details/97157638

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//判断是否是环形链表（141）
class Solution {
public:
    bool hasCycle(ListNode *head) {
        ListNode *fast = head, *slow = head;
        while(fast && fast->next){
            slow = slow->next;
            fast = fast->next->next;
            
            if(fast == slow) return true;
        }
        return false;
    }
};

//环形链表II（142）
class Solution {
public:
    ListNode *detectCycle(ListNode *head) {
        ListNode *slow = head, *fast = head;
        while (fast && fast->next) {
            slow = slow->next;
            fast = fast->next->next;
            if (slow == fast) break;
        }
        if (!fast || !fast->next) return NULL;
        slow = head;
        while (slow != fast) {
            slow = slow->next;
            fast = fast->next;
        }
        return fast;
    }
};