判断两颗树是否相同

tag: 二叉树

 

package com.zhaochao.tree;import java.util.Stack;/*** Created by zhaochao on 17/1/24.* 两颗树相等，意味着 对应节点的值相等，且具备相同的左右子树*/
public class JudgeSameTree {//recursion
public boolean isSame(TreeNode rootA, TreeNode rootB) {if(rootA == null && rootB == null) {return true;}if(rootA == null || rootB == null) {return false;}if(rootA.val != rootB.val) {return false;}return isSame(rootA.left, rootB.left) && isSame(rootA.right, rootB.right);
}public boolean isSameTraversal(TreeNode rootA, TreeNode rootB) {if(rootA == null && rootB == null) {return true;}if(rootA == null || rootB == null) {return false;}if(rootA.val != rootB.val) {return false;}Stack<TreeNode> stackA = new Stack<TreeNode>();Stack<TreeNode> stackB = new Stack<TreeNode>();stackA.push(rootA);stackB.push(rootB);while((!stackA.isEmpty() && !stackB.isEmpty())) {TreeNode nodeA = stackA.pop();TreeNode nodeB = stackB.pop();if(nodeA.val != nodeB.val) {return false;}if(nodeA.right != null && nodeB.right != null) {stackA.push(nodeA.right);stackB.push(nodeB.right);}else if(nodeA.right != null || nodeB.right != null) {return false;}if(nodeA.left != null && nodeB.left != null) {stackA.push(nodeA.left);stackB.push(nodeB.left);}else if(nodeA.left != null || nodeB.left != null) {return false;}}return true;}public static void main(String[] args) {TreeNode root = new TreeNode(0);TreeNode node1 = new TreeNode(1);TreeNode node2 = new TreeNode(2);TreeNode node3 = new TreeNode(3);//TreeNode node4 = new TreeNode(4);root.left = node1;root.right = node2;node2.left = node3;//node3.left = node4;TreeNode roota = new TreeNode(0);TreeNode nodea1 = new TreeNode(1);TreeNode nodea2 = new TreeNode(2);TreeNode nodea3 = new TreeNode(3);roota.left = nodea1;roota.right = nodea2;nodea2.left = nodea3;JudgeSameTree test  =  new JudgeSameTree();boolean result = test.isSameTraversal(root,roota);System.out.println(" is same : " + result);}}