链表的定义
链表是有序的列表，它在内存中的存储不一定是连续的，有如下几个特点：
关于链表的几个操作
以下定义都是基于带头节点的链表去实现的(头节点的number值为0)
链表的定义：
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public class Node { public int number; public Node next; public Node(int number) { this.number = number; } }
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#### [](#%E9%93%BE%E8%A1%A8%E7%9A%84%E5%9F%BA%E7%A1%80%E6%93%8D%E4%BD%9C%EF%BC%88%E5%A2%9E%E5%88%A0%E6%94%B9%E6%9F%A5%EF%BC%89 "链表的基础操作(增删改查)")链表的基础操作(增删改查)
| ```
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``` | ```
public class TestLinkedList { //头节点 private static Node head = new Node(0); public static void main(String[] args) { Node node1 = new Node(1); Node node2 = new Node(2); Node node3 = new Node(3); Node node4 = new Node(4); Node node5 = new Node(5); addByOrder(node1); addByOrder(node2); addByOrder(node4); addByOrder(node3); addByOrder(node5); display(head); // modifyNumber(5,100); // display(head); // System.out.println("删除节点之前的长度为："+length(head)); // // delete(3); // display(head); // // System.out.println("删除节点之后的长度为："+length(head)); // Node revertNode = revert(head); // display(revertNode); revertPrint(head); } /** * 向链表中添加元素 * @param node */ public static void add(Node node){ Node temp = head; while (temp.next != null){ temp = temp.next; } temp.next = node; } /** * 按照元素大小值排列添加元素 * @param node */ public static void addByOrder(Node node){ boolean flag = false; Node temp = head; while (temp.next != null){ if (temp.next.number > node.number){ flag = true; break; } temp = temp.next; } if (flag){ Node nextNode = temp.next; temp.next = node; node.next = nextNode; }else{ temp.next = node; } } /** * 打印链表中的元素 * @param node */ public static void display(Node node){ if (node == null){ System.out.println("链表为空"); } Node temp = node.next; while (temp != null ){ System.out.print(temp.number + ","); temp = temp.next; } System.out.println(); } /** * 修改链表中指定索引的node的值 * @param index 要修改的索引下标 * @param newNum 需要修改的新值 */ public static void modifyNumber(int index ,int newNum){ Node temp = head; int indexSum = 1; while (temp.next != null){ if (index == indexSum){ temp.next.number = newNum; break; } indexSum ++; temp = temp.next; } } /** * 删除一个node * @param index 需要删除的索引下标 */ public static void delete(int index){ Node temp = head; int indexSum = 1; while (temp.next != null){ if (index == indexSum){ temp.next = temp.next.next; break; } indexSum ++; temp = temp.next; } } /** * 计算链表的长度 * @param node * @return */ public static int length(Node node){ int result = 0; while (node.next != null){ result++; node = node.next; } return result; } }
``` |
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##### [](#%E5%B0%86%E9%93%BE%E8%A1%A8%E5%8F%8D%E8%BD%AC "将链表反转")将链表反转
| ```
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``` | ```
/** * 将链表反转 * @return */ public static Node revert(Node node){ if (node.next == null){ return null; } Node revertNode = new Node(0); Node cur = node.next; Node next = null; while (cur!=null){ //1.保存下一个节点指针 next = cur.next; //2.将当前节点的下一个节点指向新节点的下一个节点 cur.next = revertNode.next; //3.新节点的下一个节点指向当前节点 revertNode.next = cur; //4.当前节点为下一个节点，继续执行循环 cur = next; } return revertNode; }
``` |
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##### [](#%E5%B0%86%E9%93%BE%E8%A1%A8%E5%8F%8D%E5%90%91%E6%89%93%E5%8D%B0%EF%BC%88%E7%94%A8stack%E7%9A%84%E6%96%B9%E5%BC%8F%EF%BC%89 "将链表反向打印(用stack的方式)")将链表反向打印(用stack的方式)
| ```
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``` | ```
/** * 将链表反向打印(stack方式) */ public static void revertPrint(Node node){ Node temp = node.next; Stack<Node> stack = new Stack<>(); while (temp!= null){ stack.push(temp); temp = temp.next; } while (stack.size() > 0){ Node pop = stack.pop(); System.out.println(pop.number); } }
``` |
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##### [](#%E9%80%92%E5%BD%92%E6%89%93%E5%8D%B0%E9%93%BE%E8%A1%A8 "递归打印链表")递归打印链表
| ```
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``` | ```
public static void printDigui(Node node){ if (node.number != 0) { System.out.println(node.number); } if (node.next != null){ printDigui(node.next); } }
``` |
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##### [](#%E5%B0%86%E9%93%BE%E8%A1%A8%E5%8F%8D%E5%90%91%E6%89%93%E5%8D%B0%EF%BC%88%E7%94%A8%E9%80%92%E5%BD%92%E7%9A%84%E6%96%B9%E5%BC%8F%EF%BC%89 "将链表反向打印(用递归的方式)")将链表反向打印(用递归的方式)
| ```
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``` | ```
//默认认为头节点的number的值为0 public static void printDigui(Node node){ if (node.next != null){ printDigui(node.next); } if (node.number != 0) { System.out.println(node.number); } }
``` |
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##### [](#%E5%B0%86%E9%93%BE%E8%A1%A8%E4%B8%A4%E4%B8%A4%E5%8F%8D%E8%BD%AC "将链表两两反转")将链表两两反转
| ```
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``` | ```
/** * 链表两两反转 * @param node * @return */ public static Node revertNode(Node node){ Node head = node; while(head.next != null && head.next.next != null){ // 开始反转 Node next1 = head.next; Node next2 = next1.next; head.next = next2; next1.next = next2.next; next2.next = next1; // dummy 指针前移 head = next1; } return head; }
``` |
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