102 lines
3.0 KiB
Java
102 lines
3.0 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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* 反转单链表
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*
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* @author ehlxr
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* @since 2022-03-14 07:05.
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*/
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public class ReverseLinkedList {
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public static void main(String[] args) {
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ListNode ListNode5 = new ListNode(5, null);
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ListNode ListNode4 = new ListNode(4, ListNode5);
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ListNode ListNode3 = new ListNode(3, ListNode4);
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ListNode ListNode2 = new ListNode(2, ListNode3);
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ListNode head = new ListNode(1, ListNode2);
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// ListNode reverse = reverse(root);
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// reverse.print();
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// System.out.println(reverseToN(head, ListNode3));
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// System.out.println(reverseToN(head, 2));
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System.out.println(reverseFm2N(head, 2, 4));
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}
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public static ListNode reverseToN(ListNode root, ListNode n) {
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ListNode pre = null, cur = root, tmp = root;
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while (cur != n) {
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tmp = cur.next;
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cur.next = pre;
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pre = cur;
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cur = tmp;
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}
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return pre;
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}
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static ListNode next = null;
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public static ListNode reverseToN(ListNode root, int n) {
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if (n == 1) {
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next = root.next;
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return root;
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}
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ListNode h = reverseToN(root.next, n - 1);
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root.next.next = root;
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root.next = next;
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return h;
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}
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public static ListNode reverseFm2N(ListNode root, int m, int n) {
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if (m == 1) {
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return reverseToN(root, n);
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}
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root.next = reverseFm2N(root.next, m - 1, n - 1);
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return root;
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}
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public static ListNode reverse(ListNode root) {
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ListNode pre = null;
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ListNode cur = root;
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while (cur != null) {
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ListNode tmp = cur.next;
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cur.next = pre;
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pre = cur;
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cur = tmp;
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// tmp = cur.next;
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}
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return pre;
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}
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}
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