前言
简单的说一下两种表的结构,和他们的反转方法
一、单链表是什么?
只能单向移动的链表1.定义节点
public static class Node {
public int value;//值
public Node next;//指向下一个的引用
public Node(int data) {
//构造函数
this.value = data;
}
}
2.遍历
public static void printLinkedList(Node head) {
System.out.print("Linked List: ");
while (head != null) {
System.out.print(head.value + " ");
head = head.next;
}
System.out.println();
}
3.反转
public static Node reverseList(Node head) {
//返回反转之后的头节点
Node pre = null;//这个引用是用来指向反转过程中的头部
Node next = null;//这个指针一直指向原链表,不断在第一个和第二个之间动
while (head != null) {
next = head.next;//将next放到第二个节点
head.next = pre;//将原链表的第一个节点联想反转后的链表的尾节点
pre = head;//使它往后移一个,一直指向尾部
head = next;//回到原链表
}
return pre;
}
二、双向链表是什么
1.定义节点
public static class DoubleNode {
public int value;
public DoubleNode last;//区别就是两个指针了
public DoubleNode next;
public DoubleNode(int data) {
this.value = data;
}
}
2.遍历
//区别就是从左到右,从右到左遍历了两次
public static void printDoubleLinkedList(DoubleNode head) {
System.out.print("Double Linked List: ");
DoubleNode end = null;
while (head != null) {
System.out.print(head.value + " ");
end = head;
head = head.next;
}
System.out.print("| ");
while (end != null) {
System.out.print(end.value + " ");
end = end.last;
}
System.out.println();
}
3.反转
public static DoubleNode reverseList(DoubleNode head) {
DoubleNode pre = null;
DoubleNode next = null;
//基本过程和单链表一样,只不过每次多了一个执政换
while (head != null) {
next = head.next;
head.next = pre;
head.last = next;
pre = head;
head = next;
}
return pre;
}