50 lines
1.1 KiB
JavaScript
50 lines
1.1 KiB
JavaScript
/**
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* https://leetcode.cn/problems/linked-list-cycle/?envType=study-plan-v2&envId=top-interview-150
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* Definition for singly-linked list.
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* function ListNode(val) {
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* this.val = val;
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* this.next = null;
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* }
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*/
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/**
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* @param {ListNode} head
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* @return {boolean}
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*/
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const hasCycle = function (head) {
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};
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/*
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利用set来检测在遍历的过程中是否发生了重复，如果发生了重复说明有环，如果没有表示无环
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*/
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function f1(head) {
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const seenNodes = new Set();
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let curNote = head;
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while (curNote !== null) {
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if (seenNodes.has(curNote)) return true; // 之前遍历出现过，直接判定有环
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seenNodes.add(curNote);
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curNote = curNote.next;
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}
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return false; // 遍历了整个链表也没有发生重复，表示无环
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}
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/*
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通过快慢指针来判断是否有环
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*/
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function f2(head) {
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let slow = head;
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let fast = head;
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while (fast !== null && fast.next !== null) {
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slow = slow.next;
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fast = fast.next.next;
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if (slow === fast) return true; // 如果快慢指针相遇，表示有环
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}
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return false; // 如果快指针走到了链表末尾，表示没有环
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}
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