LinkedList.java

package task0312.coding.basic.linkedlist;

import java.util.Arrays;
import java.util.NoSuchElementException;

import javax.management.RuntimeErrorException;

import task0228.coding.basic.Iterator;
import task0228.coding.basic.List;



public class LinkedList implements List {
	private Node head;
	private int size;

	public void add(Object o) {
		// 判断头是否有数据
		if (head == null) {
			head = new Node(o, null);
		} else {
			Node newNode = head;
			while (newNode.next != null) {
				newNode = newNode.next;
			}
			newNode.next = new Node(o, null);
		}
		size++;
	}

	public void add(int index, Object o) {
		if (index < 0 || index > size) {
			throw new IndexOutOfBoundsException("index:" + index + "size:" + size);
		}
		Node node = head;
		if (index != 0) {
			// 不是第一个索引值就找到索引值的前面一个节点
			for (int i = 1; i < index; i++) {
				node = node.next;
			}
			Node newNode = new Node(o, node.next);
			node.next = newNode;
			size++;
		} else {
			// 第一个索引值就将头节点指向它
			Node newNode = new Node(o, head);
			head = newNode;
			size++;
		}
	}

	public Object get(int index) {
		indexCheck(index);
		Node node = head;
		for (int i = 1; i <= index; i++) {
			node = node.next;
		}
		return node.data;
	}

	public Node getNode(int index) {
		indexCheck(index);
		Node node = head;
		int i = 0;
		while (i++ < index) {
			node = node.next;
		}
		return node;
	}

	public Object remove(int index) {
		indexCheck(index);
		Node node = head;
		Node removeNode;
		if (index == 0) {
			// 删除第一个节点就把头节点指向原本的第二个节点
			removeNode = head;
			head = head.next;
		} else {
			// 找到索引值的前一个节点
			for (int i = 1; i < index; i++) {
				node = node.next;
			}
			removeNode = node.next;
			// 前一个节点指针，指向被删除节点所指向的节点
			node.next = removeNode.next;
		}
		size--;
		return removeNode.data;
	}

	public int size() {
		return size;
	}

	public void addFirst(Object o) {
		Node newNode = new Node(o, head.next);
		head.next = newNode;
		size++;
	}

	public void addLast(Object o) {
		add(o);
	}

	public Object removeFirst() {
		// 没有元素就抛异常
		if (size <= 0) {
			throw new IndexOutOfBoundsException("size:" + size);
		}
		Object val = head.data;
		head = head.next;
		size--;
		return val;
	}

	public Object removeLast() {
		if (size <= 0) {
			throw new IndexOutOfBoundsException("size:" + size);
		}
		Node node = head;
		while (node.next != null) {
			node = node.next;
		}
		Object val = node.data;
		node = null;
		size--;
		return val;
	}

	public Iterator iterator() {
		return new MyIterator(this);
	}

	private class MyIterator implements Iterator {
		private int poi = -1;
		private LinkedList list;

		private MyIterator(LinkedList list) {
			this.list = list;
		}

		@Override
		public boolean hasNext() {
			// TODO Auto-generated method stub
			return (poi + 1) < list.size;
		}

		@Override
		public Object next() {
			// TODO Auto-generated method stub
			poi++;
			if (poi >= list.size) {
				poi--;
				throw new IndexOutOfBoundsException();
			}

			return list.get(poi);
		}

		@Override
		public Object remove() {
			// TODO Auto-generated method stub
			if (poi < 0) {
				throw new NoSuchElementException();
			}
			Object val = list.removeLast();
			poi--;
			return val;
		}
	}

	private void indexCheck(int index) {
		if (index < 0 || index >= size) {
			throw new IndexOutOfBoundsException("index:" + index + "size:" + size);
		}
	}

	private static class Node {
		Object data;
		Node next;

		Node(Object data, Node next) {
			this.data = data;
			this.next = next;
		}
	}

	/**
	 * 把该链表逆置 例如链表为 3->7->10 , 逆置后变为 10->7->3
	 */
	public void reverse() {
		if (size == 0) {
			return;
		}
		Node node = head;
		Node node2 = new Node(head.data, null);
		while (node.next != null) {
			node = node.next;
			node2 = new Node(node.data, node2);
		}
		head = node2;
	}

	/**
	 * 删除一个单链表的前半部分 例如：list = 2->5->7->8 , 删除以后的值为 7->8 如果list = 2->5->7->8->10
	 * ,删除以后的值为7,8,10
	 * 
	 */
	public void removeFirstHalf() {
		if (size == 0) {
			return;
		}
		int i = size() / 2;
		Node node = getNode(i);
		head = node;
		size -= i;
	}

	/**
	 * 从第i个元素开始， 删除length 个元素 ， 注意i从0开始
	 * 
	 * @param i
	 * @param length
	 */
	public void remove(int i, int length) {
		indexCheck(i);
		if (size == 0 || length <= 0) {
			return;
		}
		if (length >= size) {
			if (i == 0) {
				head = null;
				size = 0;
			} else if (i == 1) {
				head.next = null;
				size = 1;
			} else {
				Node node = getNode(i - 1);
				node.next = null;
				size = i;
			}
		} else {
			// lenth>0 &length<size
			if (i == 0) {
				Node node = getNode(length);
				head = node;
			} else if (i == 1) {
				head.next = getNode(i + length);
			} else {
				getNode(i - 1).next = getNode(i + length);
			}
			size -= length;
		}

	}

	/**
	 * 假定当前链表和list均包含已升序排列的整数 从当前链表中取出那些list所指定的元素 例如当前链表 =
	 * 11->101->201->301->401->501->601->701 listB = 1->3->4->6
	 * 返回的结果应该是[101,301,401,601]
	 * 
	 * @param list
	 */
	public int[] getElements(LinkedList list) {
		if (list == null) {
			return new int[0];
		}
		int[] result = new int[list.size()];
		Node node = head;
		int len = 0;
		int count = 0;
		for (int i = 0; i < list.size(); i++) {		
			int index = (int) list.get(i);
			if(index<0 || index>=size()){
				throw new NullPointerException("index:"+index);
			}
				while (count < index) {
					node = node.next;
					count++;
				}
				result[i] =(int)node.data;
				len++;
			
		}
		result = Arrays.copyOf(result, len);
		return result;
	}

	/**
	 * 已知链表中的元素以值递增有序排列，并以单链表作存储结构。 从当前链表中中删除在list中出现的元素
	 * 
	 * @param list
	 */

	public void subtract(LinkedList list) {
		for (int i = 0; i < size(); i++) {
			for (int j = 0; j < list.size(); j++) {
				if (get(i).equals(list.get(j))) {
					remove(i--);
				}

			}
		}
	}

	/**
	 * 已知当前链表中的元素以值递增有序排列，并以单链表作存储结构。 删除表中所有值相同的多余元素（使得操作后的线性表中所有元素的值均不相同）
	 */
	public void removeDuplicateValues() {
		if (size == 0 || size == 1) {
			return;
		}
		Node node = head;
		while (node.next != null) {
			if (node.data == node.next.data) {
				node.next = node.next.next;
				size--;
			} else {
				node = node.next;
			}
		}
	}

	/**
	 * 已知链表中的元素以值递增有序排列，并以单链表作存储结构。 试写一高效的算法，删除表中所有值大于min且小于max的元素（若表中存在这样的元素）
	 * 
	 * @param min
	 * @param max
	 */
	public void removeRange(int min, int max) {
		if (size == 0 || min >= max) {
			return;
		}
		Node node = head;
		int nodeValue = ((Integer) node.data).intValue();
		// 头开始元素值大于min
		while (nodeValue > min && nodeValue < max) {
			node = node.next;
			size--;
			if (node == null) {
				head = null;
				size = 0;
				return;
			}
			nodeValue = ((Integer) node.data).intValue();
		}
		head = node;// 当元素值大于等于max就跳出循环赋值给head
		// 头开始元素值小于min
		if (nodeValue < min) {
			while (nodeValue < min) {// 遍历直到元素值大于min
				node = node.next;
				if (node.next == null) {// 最后元素值都比min小
					return;
				}
				nodeValue = ((Integer) node.data).intValue();
			}
			if (node.next == null) {
				return;
			}
			Node temp = new Node(null, node);// 大于min的不是最后元素则用temp.next记录当前位置
			node = node.next;
			nodeValue = ((Integer) node.data).intValue();
			while (nodeValue < max) {
				node = node.next;
				size--;
				if (node == null) {
					temp.next.next = node;
					return;
				}
				nodeValue = ((Integer) node.data).intValue();
			}
			temp.next.next = node;
		}
	}

	/**
	 * 假设当前链表和参数list指定的链表均以元素依值递增有序排列（同一表中的元素值各不相同）
	 * 现要求生成新链表C，其元素为当前链表和list中元素的交集，且表C中的元素有依值递增有序排列
	 * 
	 * @param list
	 */
	public LinkedList intersection(LinkedList list) {
		if (list == null) {
			return list;
		}
		LinkedList result = new LinkedList();
		for (int i = 0; i < size(); i++) {
			for (int j = 0; j < list.size(); j++) {
				if (get(i).equals(list.get(j))) {
					result.add(get(i));
					break;
				}
			}
		}
		return result;
	}

	public String toString() {
		StringBuffer sb = new StringBuffer();
		sb.append("[");
		for (int i = 0; i < size(); i++) {
			if (i == size() - 1) {
				sb.append(get(i));
				break;
			}
			sb.append(get(i));
			sb.append(",");
		}
		sb.append("]");
		return sb.toString();
	}
}