《算法（第四版）》1.3.31 双向链表

最新推荐文章于 2020-07-20 09:08:10 发布

原创最新推荐文章于 2020-07-20 09:08:10 发布 · 380 阅读

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CC 4.0 BY-SA版权

本文介绍了一个自定义双向链表的数据结构实现，包括节点的插入、删除等操作，并提供了迭代器支持。通过具体示例展示了如何使用该双向链表进行元素的增删查改。

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package Cap1;

import java.util.Iterator;

import edu.princeton.cs.introcs.StdOut;
import edu.princeton.cs.introcs.StdRandom;

public class DoubleNode<Item> implements Iterable<Item> {

	/**
	 * @param args
	 */
	private Node first=null, last = null;
	private class Node {
		Item item;
		Node prev,next;
	}
	public void push_front(Item item){
		Node node = new Node();
		node.item = item;
		if(first == null){
			first = node;
			last = node;
		}
		else{
			first.prev = node;
			node.next = first;
			first = node;
		}
	}
	public void push_back(Item item){
		Node node = new Node();
		node.item = item;
		if(last == null){
			first = node;
			last = node;
		}
		else{
			last.next = node;
			node.prev = last;
			last = node;
		}
	}
	public Item pop_back(){
		
		if(last == null) return null;
		else{
			Item item = last.item;
			last = last.prev;
			last.next.prev = null;
			last.next = null;
			return item;
		}
	}
	public Item pop_front(){
		
		if(first == null) return null;
		else{
			Item item = first.item;
			first = first.next;
			first.prev.next = null;
			first.prev = null;
			return item;
		}
	}
	private void remove(Node cur){
		if(cur==null) return;
		if(cur==first){
			first = first.next;
			first.prev = null;
		}
		else if(cur == last){
			last = last.prev;
			last.next = null;
		}
		else{
			cur.prev.next = cur.next;
			cur.next.prev = cur.prev;
		}
		cur.prev = null;
		cur.next = null;
	}
	public void remove(int k){
		Node cur = first;
		for(int i=1;i<k && cur!=null;i++){
			cur = cur.next;
		}
		remove(cur);
	}
	public void remove(Item item){
		Node cur;
		for(cur = first;cur!=null && cur.item!=item ;cur = cur.next);
		if(cur == null) return;
		remove(cur);
	}
	public void removeBefore(Item item){
		Node cur;
		for(cur = first;cur!=null && cur.item!=item;cur = cur.next);	 
		if(cur == null) return; // not find the node
		remove(cur.prev); // delete the node before cur;
	}
	public void removeAfter(Item item){
		Node cur;
		for(cur = first;cur!=null && cur.item!=item;cur = cur.next);
		if(cur == null) return;
		remove(cur.next); // delete the node before cur;
	}
	
	@Override
	public Iterator<Item> iterator() {
		// TODO Auto-generated method stub
		return new DoubleNodeIterator();
	}
	private class DoubleNodeIterator implements Iterator<Item>{

		private Node cur = first;
		@Override
		public boolean hasNext() {
			// TODO Auto-generated method stub
			return cur != null;
		}

		@Override
		public Item next() {
			// TODO Auto-generated method stub
			Item item = cur.item;
			cur = cur.next;
			if(cur!=null){
				cur.prev.next = null;
				cur.prev = null;
			}
			
			return item;
		}

		@Override
		public void remove() {
			// TODO Auto-generated method stub
			
		}
		
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		DoubleNode<Integer> dn = new DoubleNode<Integer>();
		for(int i=0;i<10;i++){
			dn.push_back(i*10);
		}
		dn.removeAfter(Integer.valueOf(80));
		dn.pop_front();
		dn.pop_back();
		for(Integer d : dn){
			StdOut.println(d);
		}
	}
	

}