問題描述：求二叉樹中距離最遠的兩個 節點之間的距離。。

class Node{
	public int data;
	public Node left;
	public Node right;
	public int leftMaxDistance;
	public int rightMaxDistance;
	public Node(int data){
		this.data=data;
		this.left=null;
		this.right=null;
	}
}

public class BinaryTree{

	private int maxLen=0;
	private Node root;
	
	public BinaryTree() {
		root=null;
	}

	private int max(int a,int b){
		return a>b?a:b;
	}
	
	private  void FindMaxDistance(Node root){
		if(root==null)
			return ;
		if(root.left==null)
			root.leftMaxDistance=0;
		if(root.right==null)
			root.rightMaxDistance=0;
		if(root.left!=null)
			FindMaxDistance(root.left);
		if(root.right!=null)
			FindMaxDistance(root.right);
		if(root.left!=null){
			root.leftMaxDistance=max(root.left.leftMaxDistance,root.left.leftMaxDistance)+1;
		}
		if(root.right!=null){
			root.rightMaxDistance=max(root.right.rightMaxDistance,root.right.rightMaxDistance)+1;
		}
		if(root.leftMaxDistance+root.rightMaxDistance>maxLen){
			maxLen=root.leftMaxDistance+root.rightMaxDistance;
		}
	}
	
	//向二叉排序樹插入節點
	private void insertBtree(int data){
		Node newNode=new Node(data);
		if(root==null){
			root=newNode;
		}else{
			Node current=root;
			Node parent;
			while(true){
				parent=current;
				if(data<current.data){
					current=current.left;
					if(current==null){
						parent.left=newNode;
						return;
					}
				}else{
					current=current.right;
					if(current==null){
						parent.right=newNode;
						return;
					}
				}
			}//while
		}
	}
	
	//將數值輸入構建二叉樹
	public void buildTree(int[] data){
		for (int i = 0; i < data.length; i++) {
			insertBtree(data[i]);
		}
	}
 

//層序遍歷二叉樹
public void layerTranverse(){
if(this.root==null){
return;
}
Queue<Node> q=new LinkedList<Node>();
q.add(this.root);
while(!q.isEmpty()){
Node n=q.poll();
System.out.print(n.data+" ");
if(n.left!=null)
q.add(n.left);


if(n.right!=null)
q.add(n.right);
}
}
	
	public static void main(String[] args) {
		int[] data={5,3,2,4,7,6,8};
		BinaryTree bTree=new BinaryTree();
		bTree.buildTree(data);
		bTree.FindMaxDistance(bTree.root);
		System.out.println(bTree.maxLen);

		bTree.layerTranverse();

	}
}