/**

* 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) {

Queue<TreeNode> queue = new LinkedList<>();

queue.add(p);

queue.add(q);

while(!queue.isEmpty()){

TreeNode l = queue.poll();

TreeNode r = queue.poll();

if(l == null && r == null) continue;

else if(l == null || r == null || l.val != r.val) return false;

queue.add(l.left);

queue.add(r.left);

queue.add(l.right);

queue.add(r.right);

}

return true;

}

public boolean isSameTree(TreeNode p, TreeNode q) {

if (p == null && q == null) return true;

else if(p == null || q == null || p.val != q.val) return false;

return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);

}

}