leetcode -hasLinkedListCycle

Leetcode题解之 —— 环形链表

思路

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追及问题

• 快慢指针

题解

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/**
 * @param {ListNode} head
 * @return {boolean}
 */
var hasCycle = function(head) {
  // TODO 追击问题

  let [slow, fast, flag] = [head, head, false];

  while (fast && fast.next) {
    fast = fast.next.next;
    slow = slow.next;

    if (fast == slow) {
      flag = true;
      break;
    }
  }

  return flag;
};