[数据结构]环形链表

面试题 02.08. 环路检测

141. 环形链表

实现1:

var hasCycle = function(head) {
    if (head == null || head.next == null) return false;
    let fast = head.next;
    let slow = head;
    while (fast != null) {
        if (fast == slow) return true;
        if (fast.next == null || fast.next.next == null) return false;
        slow = slow.next;
        fast = fast.next.next;
    }
    return false;
};

实现2:

var hasCycle = function(head) {
    if (head == null || head.next == null) return false;
    let fast = head.next;
    let slow = head;
    while (fast != slow) {
        if (fast == null || fast.next == null) return false;
        fast = fast.next.next;
        slow = slow.next;
    }
    return true;
};

142. 环形链表 II