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leetcode 206 reverse List

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ehlxr 2021-02-27 22:59:21 +08:00
parent 55d8f3b68f
commit b3cd375f61
3 changed files with 190 additions and 0 deletions
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56
src/main/java/io/github/ehlxr/leetcode/ListNode.java Normal file
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/*
* The MIT License (MIT)
*
* Copyright © 2020 xrv <xrg@live.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package io.github.ehlxr.leetcode;
/**
* 链表结构
*
* @author ehlxr
* @since 2021-02-27 21:09.
*/
public class ListNode {
int val;
ListNode next;
ListNode() {
}
ListNode(int val) {
this.val = val;
}
ListNode(int val, ListNode next) {
this.val = val;
this.next = next;
}
@Override
public String toString() {
return "ListNode{" +
"val=" + val +
", next=" + next +
'}';
}
}

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src/main/java/io/github/ehlxr/leetcode/Solution206.java Normal file
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/*
* The MIT License (MIT)
*
* Copyright © 2020 xrv <xrg@live.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package io.github.ehlxr.leetcode;
/**
* 反转链表
* 假设链表为 1 → 2 → 3 → null，我们想要把它改成 null ← 1 ← 2 ← 3
*
* @author ehlxr
* @since 2021-02-27 21:08.
*/
public class Solution206 {
/*
方法一：迭代
https://leetcode-cn.com/problems/reverse-linked-list/solution/fan-zhuan-lian-biao-by-leetcode-solution-d1k2/
*/
public static ListNode reverseList1(ListNode head) {
ListNode prev = null;
while (head != null) {
// 先存储当前节点的下一个节点
ListNode next = head.next;
// 将当前节点的下一个节点改为前一个节点
head.next = prev;
// 指针后移
// 更改前一个节点为当前节点
prev = head;
// 更改当前节点为下一个节点
head = next;
}
return prev;
}
/*
方法一：递归
https://leetcode-cn.com/problems/reverse-linked-list/solution/shi-pin-jiang-jie-die-dai-he-di-gui-hen-hswxy/
*/
public static ListNode reverseList2(ListNode head) {
// 递归终止条件
if (head == null || head.next == null) {
return head;
}
ListNode h = reverseList2(head.next);
head.next.next = head;
// 防止链表循环
head.next = null;
return h;
}
public static void main(String[] args) {
ListNode n1 = new ListNode(1);
ListNode n2 = new ListNode(2);
ListNode n3 = new ListNode(3);
ListNode n4 = new ListNode(4);
n1.next = n2;
n2.next = n3;
n3.next = n4;
System.out.println(n1);
System.out.println(reverseList2(n1));
}
}

43
src/main/java/io/github/ehlxr/lock/Locker.java Normal file
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/*
* The MIT License (MIT)
*
* Copyright © 2020 xrv <xrg@live.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package io.github.ehlxr.lock;
import java.util.concurrent.locks.AbstractQueuedLongSynchronizer;
import java.util.concurrent.locks.ReentrantLock;
/**
* @author ehlxr
* @since 2021-02-15 18:11.
*/
public class Locker {
public static void main(String[] args) {
ReentrantLock lock = new ReentrantLock();
lock.tryLock();
}
}