48 lines
1.3 KiB
JavaScript
48 lines
1.3 KiB
JavaScript
/**
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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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* @param {number} k
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* @return {ListNode}
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*/
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export const reverseKGroup = function (head, k) {
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let sum = 0 // 记录进行的结点个数
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let start = head // 记录每次翻转的第一个元素
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let res = head // 返回值：如果进行过翻转，则为第一次翻转的最后一个结点
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const queue = [] // 使用队列，方便连接上一次翻转的链表，最大长度为2
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while (head) { // 遍历一次链表
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if (++sum === k) { // 如果经过了k个结点，则翻转从start到head的一段结点
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const headNext = head.next
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queue.push(start) // 计入队列
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let next = head.next
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for (let i = 0; i < sum - 1; i++) { // 翻转结点
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const tmp = start.next
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start.next = next
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next = start
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start = tmp
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}
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start.next = next // 最后一个结点
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if (queue.length === 1) { // 判断是否为第一次翻转
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res = start
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} else {
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const la = queue.shift() // 连接上一次翻转的链表
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la.next = head
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}
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sum = 0 // 重置计数
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start = headNext
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head = headNext
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} else {
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head = head.next
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}
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}
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return res
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}
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