69 lines
2.2 KiB
Java
69 lines
2.2 KiB
Java
/*
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* The MIT License (MIT)
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*
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* Copyright © 2022 xrv <xrv@live.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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package io.github.ehlxr.algorithm.linkedlist;
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/**
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* @author ehlxr
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* @since 2022-05-03 14:26.
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*/
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public class ReverseKGroup {
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public static void main(String[] args) {
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ListNode head = new ListNode(1);
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head.next = new ListNode(2);
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head.next.next = new ListNode(3);
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head.next.next.next = new ListNode(4);
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head.next.next.next.next = new ListNode(5);
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System.out.println(head);
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System.out.println(reverseKGroup(head, 2));
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}
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public static ListNode reverseKGroup(ListNode head, int k) {
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ListNode p = head;
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for (int i = 0; i < k; i++) {
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if (p == null) {
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return head;
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}
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p = p.next;
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}
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ListNode r = reverseN(head, p);
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head.next = reverseKGroup(p, k);
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return r;
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}
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public static ListNode reverseN(ListNode head, ListNode n) {
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ListNode cur = head, pre = null;
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while (cur != n) {
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ListNode next = cur.next;
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cur.next = pre;
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pre = cur;
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cur = next;
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}
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return pre;
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}
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}
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