数据结构_二叉树遍历

package zz;

import java.util.ArrayList;
import java.util.List; 
import java.util.Scanner;  

class TreeNode {
    int value;
    TreeNode leftChild;
    TreeNode rightChild;
    
    public TreeNode(int value, TreeNode lc, TreeNode rc) {
        this.value = value;
        this.leftChild = lc;
        this.rightChild = rc;
    }
}

public class TreeDemo {
    //求数的深度
    public int getTreeHeight(TreeNode root) {
        if(root == null) return 0;
        if(root.leftChild == null && root.rightChild == null) return 1;
        return 1 + Math.max(getTreeHeight(root.leftChild), getTreeHeight(root.rightChild));
    }
    //递归先序遍历
    public void recPreOrder(TreeNode root) {
        if(root == null) return;
        System.out.print(root.value + " ");
        if(root.leftChild != null) 
            recPreOrder(root.leftChild);
        if(root.rightChild != null) 
            recPreOrder(root.rightChild);
    }
    //递归中序遍历
    public void recInOrder(TreeNode root) {
        if(root == null) return;
        if(root.leftChild != null)
            recInOrder(root.leftChild);
        System.out.print(root.value + " ");
        if(root.rightChild != null)
            recInOrder(root.rightChild);
    }
    //递归后序遍历
    public void recPostOrder(TreeNode root) {
        if(root == null) return;
        if(root.leftChild != null) 
            recPostOrder(root.leftChild);
        if(root.rightChild != null) {
            recPostOrder(root.rightChild);
        }
        System.out.print(root.value + " ");
    }
}