LinkedList.java

package com.coderising.basic;

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

public class LinkedList implements List {

	private Node head;
	private int size;

	public LinkedList() {
		size = 0;
		head = null;
	}

	public void add(Object o) {
		Node node = new Node(o);
		if (head == null) {
			head = node;
		} else {
			// p为游标 从头遍历到尾
			Node p = head;
			while (p.next != null) {
				p = p.next;
			}
			p.next = node;
		}
		size++;
	}

	public void add(int index, Object o) {
		// 判断不为空链表
		if (head != null) {
			Node p = head;
			int k = 0;
			// 扫描单链表查找第index-1个节点
			while (k < index - 1 && p.next != null) {
				k++;
				p = p.next;
			}
			// 判断是否找到第index-1个节点
			if (p != null) {
				Node node = new Node(o);
				node.next = p.next;
				p.next = node;
			}
			size++;
		}
	}

	public Object get(int index) {
		if (index < 0 || index >= size) {
			throw new IndexOutOfBoundsException();
		} else {
			Node p = head;
			int k = 0;
			while (k < index && p.next != null) {
				k++;
				p = p.next;
			}
			return p.data;
		}
	}

	public Object remove(int index) {
		if (index < 0 || index >= size) {
			throw new IndexOutOfBoundsException();
		}
		if (head == null) {
			return null;
		}
		if (index == 0) {
			head = head.next;
			size--;
			return head.data;
		} else {
			if (head != null) {
				int k = 0;
				Node p = head;
				while (k < index - 1 && p != null) {
					k++;
					p = p.next;
				}
				Node pn = p.next;
				if (pn != null) {
					p.next = pn.next;
					size--;
					return pn.data;
				}
			}
		}
		return null;
	}

	public int size() {
		return size;
	}

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

	public void addLast(Object o) {
		Node node = new Node(o);
		if (head == null) {
			head = node;
		} else {
			Node p = head;
			while (p.next != null) {
				p = p.next;
			}
			p.next = node;
		}
		size++;
	}

	public Object removeFirst() {
		if (head == null) {
			throw new NoSuchElementException();
		}
		Node node = head;
		head = node.next;
		size--;
		return node.data;
	}

	public Object removeLast() {
		if (head == null) {
			throw new NoSuchElementException();
		} else {
			Node p = head;
			int k = 0;
			while (k < size - 1 && p.next != null) {
				k++;
				p = p.next;
			}
			Node last = p.next;
			p.next = null;
			size--;
			return last.data;
		}
	}

	private static class Node {
		Object data;
		Node next;

		private Node(Object o) {
			this.data = o;
			this.next = null;
		}
	}

	/**
	 * 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 (null == head || null == head.next) {
			return;
		}
		Stack<Node> s = new Stack<Node>();

		Node currentNode = head;
		while (currentNode != null) {

			s.push(currentNode);

			Node nextNode = currentNode.next;
			currentNode.next = null; // 把链接断开
			currentNode = nextNode;
		}

		head = s.pop();

		currentNode = head;
		while (!s.isEmpty()) {
			Node nextNode = s.pop();
			currentNode.next = nextNode;
			currentNode = nextNode;
		}
	}

	/**
	 * 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() {
		int num = size / 2;
		for (int i = 0; i < num; i++) {
			removeFirst();
		}
	}

	/**
	 * 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) {

		if (i < 0 || i >= size) {
			throw new IndexOutOfBoundsException();
		}

		int len = size - i >= length ? length : size - i;

		int k = 0;
		while (k < len) {
			remove(i);
			k++;
		}
	}

	/**
	 * 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) {

		int[] arr = new int[list.size()];

		for (int i = 0; i < list.size(); i++) {
			arr[i] = (int) this.get((int) list.get(i));
		}
		return arr;
	}

	/**
	 * 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 < list.size(); i++) {
			this.remove(list.get(i));
		}
	}

	/**
	 * 传入数据删除节点
	 * 
	 * @param obj
	 */
	public void remove(Object obj) {
		if (head == null) {
			throw new RuntimeException("LinkedList is empty!");
		}
		// 如果要删除的结点是第一个，则把下一个结点赋值给第一个结点
		if (head.data.equals(obj)) {
			head = head.next;
			size--;
		} else {
			Node pre = head; // 上一节点
			Node cur = head.next; // 当前结点
			while (cur != null) {
				if (cur.data.equals(obj)) {
					pre.next = cur.next;
					size--;
				}
				pre = pre.next;
				cur = cur.next;
			}
		}
	}

	/**
	 * 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 (head == null) {
			throw new RuntimeException("LinkedList is empty!");
		}

		Node pre = head;
		Node cur = head;
		while (cur.next != null) {
			cur = cur.next;
			Object data = pre.data;
			while (cur.data == data) {
				if (cur.next == null) {
					pre.next = null;
					break;
				}
				pre.next = cur.next;
				size--;
				cur = cur.next;
				if (cur == null) {
					break;
				}
			}
			pre = pre.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 (head == null) {
			return;
		}

		Node node = head;
		int start = -1;
		int end = -1;
		int i = 0;
		while (node != null) {
			if ((start == -1) && (int) node.data <= min) {
				start = i;
			}
			if ((int) node.data >= max) {
				end = i;
				break;
			}
			node = node.next;
			i++;
		}

		if (start == -1) {
			start = 0;
		}
		if (end == -1) {
			end = size;
		}
		this.remove(start, end - start);

		/*
		 * if(head == null){ throw new RuntimeException("LinkedList is empty!");
		 * }else{ Node q = head; //头判断 if((int)q.data>min && (int)q.data<max){
		 * head = head.next; size--; removeRange(min, max); return; }
		 * 
		 * Node p = q.next; while(p!=null){ if((int)p.data>min &&
		 * (int)p.data<max){ size--; q.next = p.next; } q = q.next; p = q.next;
		 * } }
		 */
	}

	public String toString() {
		StringBuffer buffer = new StringBuffer();
		buffer.append("[");
		Node node = head;
		while (node != null) {
			buffer.append(node.data);
			if (node.next != null) {
				buffer.append(",");
			}
			node = node.next;
		}
		buffer.append("]");
		return buffer.toString();
	}

	/**
	 * 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 null;
		}

		LinkedList result = new LinkedList();

		int i1 = 0;
		int i2 = 0;

		while (i1 < this.size && i2 < list.size()) {

			int value1 = (int) this.get(i1);
			int value2 = (int) list.get(i2);

			if (value1 == value2) {
				result.add(value1);
				i1++;
				i2++;

			} else if (value1 < value2) {
				i1++;

			} else {
				i2++;

			}
		}

		return result;

		/*
		 * LinkedList linkedList = new LinkedList();
		 * intersection(linkedList,this.head, list.head); return linkedList;
		 */
	}

	private void intersection(LinkedList linkedList, Node node1, Node node2) {
		if (node1 == null) {
			while (node2 != null) {
				linkedList.add(node2.data);
				node2 = node2.next;
			}
		} else if (node2 == null) {
			while (node1 != null) {
				linkedList.add(node1.data);
				node1 = node1.next;
			}
		} else {
			if ((int) node1.data < (int) node2.data) {
				linkedList.add(node1.data);
				intersection(linkedList, node1.next, node2);
			} else {
				linkedList.add(node2.data);
				intersection(linkedList, node1, node2.next);
			}
		}
	}

	public static void main(String[] args) {
		LinkedList linkedList = new LinkedList();
		linkedList.add(11);
		linkedList.add(101);
		linkedList.add(201);
		linkedList.add(301);
		linkedList.add(401);
		linkedList.add(501);
		linkedList.add(601);
		linkedList.add(701);
		LinkedList list = new LinkedList();
		list.add(1);
		list.add(3);
		list.add(4);
		list.add(6);
		System.out.println(Arrays.toString(linkedList.getElements(list)));
	}
}