1. 递归

2. 栈

package org.skyeye.test;

import java.util.Stack;

public class TreeSwap {

public static class Tree{

private Object data;

private Tree left;

private Tree right;

public Tree(Object data, Tree left, Tree right) {

this.data = data;

this.left = left;

this.right = right;

}

public Object getData() {

return data;

}

public void setData(Object data) {

this.data = data;

}

public Tree getLeft() {

return left;

}

public void setLeft(Tree left) {

this.left = left;

}

public Tree getRight() {

return right;

}

public void setRight(Tree right) {

this.right = right;

}

}

public static int getMaxDepth(Tree root) {

if(root==null) {

return 0;

}

return Math.max(getMaxDepth(root.left), getMaxDepth(root.right))+1;

}

public static void swap1(Tree root) {

if(root == null) {

return;

}

Tree tmp = root.left;

root.left = root.right;

root.right = tmp;

swap1(root.left);

swap1(root.right);

}

public static void swap2(Tree root) {

if(root==null) {

return;

}

Stack stack = new Stack();

stack.push(root);

while(!stack.empty()) {

Tree node = stack.pop();

Tree tmp = node.left;

node.left = node.right;

node.right = tmp;

if(node.left!=null) {

stack.push(node.left);

}

if(node.right!=null) {

stack.push(node.right);

}

}

}

public static void main(String[] args) {

Tree lll = new Tree(1, null, null);

Tree ll = new Tree(2, lll, null);

Tree lr = new Tree(3, null, null);

Tree l = new Tree(4, ll, lr);

Tree rl = new Tree(7, null, null);

Tree rr = new Tree(8, null, null);

Tree r = new Tree(6, rl, rr);

Tree root = new Tree(5, l, r);

swap2(root);

System.out.println(root);

}

}