用java实现二叉树

这是组合设计模式。

我有很多个(假设10万个)数据要保存起来，以后还需要从保存的这些数据中检索是否存在某个数据，（我想说出二叉树的好处，该怎么说呢？那就是说别人的缺点），假如存在数组中，那么，碰巧要找的数字位于99999那个地方，那查找的速度将很慢，因为要从第1个依次往后取，取出来后进行比较。平衡二叉树（构建平衡二叉树需要先排序，我们这里就不作考虑了）可以很好地解决这个问题，但二叉树的遍历（前序，中序，后序）效率要比数组低很多。

代码如下：

package com.huawei.interview;public class Node {public int value;public Node left;public Node right;public void store(int value){if(value<this.value){if(left == null){left = new Node();left.value=value;}else{left.store(value);}}else if(value>this.value){if(right == null){right = new Node();right.value=value;}else{right.store(value);}}}public boolean find(int value){System.out.println("happen " + this.value);if(value == this.value){return true;}else if(value>this.value){if(right == null) return false;return right.find(value);}else{if(left == null) return false;return left.find(value);}}public  void preList(){System.out.print(this.value + ",");if(left!=null) left.preList();if(right!=null) right.preList();}public void middleList(){if(left!=null) left.preList();System.out.print(this.value + ",");if(right!=null) right.preList();}public void afterList(){if(left!=null) left.preList();if(right!=null) right.preList();System.out.print(this.value + ",");}public static void main(String [] args){int [] data = new int[20];for(int i=0;i<data.length;i++){data[i] = (int)(Math.random()*100) + 1;System.out.print(data[i] + ",");}System.out.println();Node root = new Node();root.value = data[0];for(int i=1;i<data.length;i++){root.store(data[i]);}root.find(data[19]);root.preList();System.out.println();root.middleList();System.out.println();root.afterList();}}

 

import java.util.Arrays;import java.util.Iterator;public class Node {private Node left;private Node right;private int value;//private int num;public Node(int value){this.value = value;}public void add(int value){if(value > this.value){if(right != null)right.add(value);else{Node node = new Node(value);right = node;}}else{if(left != null)left.add(value);else{Node node = new Node(value);left = node;}}}public boolean find(int value){if(value == this.value) return true;else if(value > this.value){if(right == null) return false;else return right.find(value);}else{if(left == null) return false;else return left.find(value);}}public void display(){System.out.println(value);if(left != null) left.display();if(right != null) right.display();}/*public Iterator iterator(){}*/public static void main(String[] args){int[] values = new int[8];for(int i=0;i<8;i++){int num = (int)(Math.random() * 15);//System.out.println(num);//if(Arrays.binarySearch(values, num)<0)if(!contains(values,num))values[i] = num;elsei--;}System.out.println(Arrays.toString(values));Node root  = new Node(values[0]);for(int i=1;i<values.length;i++){root.add(values[i]);}System.out.println(root.find(13));root.display();}public static boolean contains(int [] arr, int value){int i = 0;for(;i<arr.length;i++){if(arr[i] == value) return true;}return false;}}