package com.wyy.test;import java.util.Stack;public class TransverseTreeWithoutDGTest {public static void main(String[] args){Tree tree = new Tree();tree.insert("A", 30);tree.insert("B", 42);tree.insert("C", 19);tree.insert("D", 22);tree.insert("E", 33);tree.insert("F", 45);tree.insert("G", 20);tree.preOrder(tree.root);System.out.println();tree.midOrder(tree.root);System.out.println();tree.lastOrder(tree.root);System.out.println();System.out.println("----------------------------");Tree.postOrderWithStack(tree.root);}
}
class Node{public String name;public int count;public Node leftChild;public Node rightChild;public Node(String name,int count){this.name = name;this.count = count;}
}
class Tree{public Node root;public Tree(){root = null;}public void insert(String name,int count){Node newNode = new Node(name,count);if(root==null)root = newNode;else{Node current = root;Node parent;while(true){parent = current;if(count<current.count){current = current.leftChild;if(current==null){parent.leftChild = newNode;return;}}else if(count>current.count){current = current.rightChild;if(current==null){parent.rightChild = newNode;return;}}}}}public Node find(int key){Node current = root;while(true){if(current==null)return null;if(key==current.count)return current;else if(key<current.count){current = current.leftChild;}else if(key>current.count){current = current.rightChild;}}}public void preOrder(Node node){if(node!=null){System.out.print(node.name);preOrder(node.leftChild);preOrder(node.rightChild);}}public void midOrder(Node node){if(node!=null){midOrder(node.leftChild);System.out.print(node.name);midOrder(node.rightChild);}}public void lastOrder(Node node){if(node!=null){lastOrder(node.leftChild);lastOrder(node.rightChild);System.out.print(node.name);}}public void preOrderWithStack(Node node){Stack<Node> s = new Stack<Node>();Node current = node;while(current!=null||!s.isEmpty()){while(current!=null){System.out.print(current.name+" ");if(current.rightChild!=null){s.push(current.rightChild);}current = current.leftChild;}if(!s.isEmpty()){current = s.pop();}}}public void inOrderWithStack(Node node){Node current = node;Stack<Node> s = new Stack<Node>();while(current!=null||!s.isEmpty()){while(current!=null){s.push(current);current = current.leftChild;}if(!s.isEmpty()){current = s.pop();System.out.print(current.name+" ");current = current.rightChild;}}}public static void postOrderWithStack(Node node){Node current;Node pre = null;Stack<Node> s= new Stack<Node>();s.push(node);while(!s.isEmpty()){current = s.peek();if((current.leftChild==null&&current.rightChild==null)||(pre!=null&&(pre==current.leftChild||pre==current.rightChild))){System.out.print(s.pop().name);//如果节点的左右子节点都为null 或者都被遍历过则可以访问pre = current;}else{if(current.rightChild!=null)s.push(current.rightChild);if(current.leftChild!=null)s.push(current.leftChild);}}}}