5、说明生活中遇到的二叉树，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，原理如下图：
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();
-----------------又一次临场写的代码---------------------------
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;
else
i--;
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;
I‘m trying to get google maps on an application on my android device. I was testing how it works so i started with adding a simple map. However when i try to run it it gives me this error.
Cannot reload AVD list: cvc-complex-type.2.4.d: Invalid content was found starting with element ‘d:skin‘. No child element is expected at this point. Error parsing /Applications/Android Studio.app/sdk/system-images/android-22/android-wear/armeabi-v7a/devices.xml cvc-complex-type.2.4.d: Invalid content was found starting with element ‘d:skin‘. No child element is expected at this point. Error parsing /Applications/Android Studio.app/sdk/system-images/android-22/android-wear/x86/devices.xm
解决方式：
点击工具栏上的 SDK Manager ---- 找到Android Wear ARM 和 Intel images 选项， 选中删除即可 ！