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# 100.Same-Tree

## 题目描述

Given two binary trees, write a function to check if they are the same or not.
Two binary trees are considered the same if they are structurally identical and the nodes have the same value.
Example 1:
Input: 1 1
/ \ / \
2 3 2 3
[1,2,3], [1,2,3]
Output: true
Example 2:
Input: 1 1
/ \
2 2
[1,2], [1,null,2]
Output: false
Example 3:
Input: 1 1
/ \ / \
2 1 1 2
[1,2,1], [1,1,2]
Output: false

## 代码

### Approach #1 Recursion

/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public boolean isSameTree(TreeNode p, TreeNode q) {
if (p == null && q == null) return true;
if (p == null || q == null) return false;
if (p.val != q.val) return false;
return isSameTree(p.right, q.right)
&& isSameTree(p.left, q.left);
}
}

### Approach #2 Iteration

class Solution {
public boolean isSameTree(TreeNode p, TreeNode q) {
if (!check(p, q)) return false;
ArrayDeque<TreeNode> deqP = new ArrayDeque<TreeNode>();
ArrayDeque<TreeNode> deqQ = new ArrayDeque<TreeNode>();
while (!deqP.isEmpty()) {
p = deqP.removeFirst();
q = deqQ.removeFirst();
if (!check(p, q)) return false;
if (p != null) {
if (!check(p.left, q.left)) return false;
if (p.left != null) {
}
if (!check(p.right, q.right)) return false;
if (p.right != null) {