基础数据结构01：链表

说明

链表的类似于一个连着一个的圆环。在链表中，要想访问某个节点，必须通过他的上一节点来访问。

Java实现

package com.algs.base;

import java.util.Iterator;
import java.util.NoSuchElementException;

public class Link implements Iterable {
    private Node first = null;  // 链表的第一个元素
    private int n = 0;          // 链表的长度

    private class Node{
        private Item item;      // 链表节点的值
        private Node next;      // 指向下一节点

        public String toString(){
            return (String) this.item;
        }
    }

    // 向链表中添加数据
    public void add(Item item){
        Node oldFirst = first;
        first = new Node();
        first.item = item;
        first.next = oldFirst;
        n++;
    }

    // 翻转链表
    public void reverse(){
        Node next = first.next;
        first.next = null;              // 避免遍历时死循环
        while(next!=null){
            Node temp = next.next;
            next.next = first;
            first = next;
            next = temp;
        }
    }

    public int size(){
        return n;
    }

    @Override
    public Iterator iterator()  {
        return new ListIterator();  
    }
    //链表遍历实现
    private class ListIterator implements Iterator {
        private Node current = first;

        public boolean hasNext()  { return current != null;                     }
        public void remove()      { throw new UnsupportedOperationException();  }

        public Item next() {
            if (!hasNext()) throw new NoSuchElementException();
            Item item = current.item;
            current = current.next;
            return item;
        }
    }

    public static void main(String[] args) {
        Link link = new Link();
        link.add("one");
        link.add("two");
        link.add("three");
        for(String node:link){
            //打印结果为three->two->one->
            System.out.print(node+"->");
        }
        //翻转链表
        System.out.println("");
        link.reverse();
        for(String node:link){
            //打印结果为one->two->three->
            System.out.print(node+"->");
        }
    }

}

GitHub：https://github.com/AlbertKnag/algs-practice

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