leetcode(面试题02.02.返回倒数第k个节点)

一.蠢办法&＃xff08;使用循环进行查找&＃xff09;

var kthToLast &＃61; function(head, k) {var dummy &＃61; new ListNode(0);dummy &＃61; head;var length &＃61; 0;while(dummy!&＃61;null){length&＃43;&＃43;;dummy &＃61; dummy.next;}console.log("长度为:"&＃43;length);var buchang &＃61; 0;var didian &＃61; length - k;while(buchang !&＃61; didian){buchang&＃43;&＃43;;head &＃61; head.next;}return head.val;
};

二.使用快慢指针

var kthToLast &＃61; function(head, k) {var fast &＃61; new ListNode(0);var slow &＃61; new ListNode(0);fast &＃61; head;slow &＃61; head;while(k!&＃61;0){fast &＃61; fast.next;k--;}while(fast!&＃61;null){fast&＃61;fast.next;slow &＃61; slow.next;}return slow.val;
};