/**

* Definition for binary tree

* public class TreeNode {

* int val;

* TreeNode left;

* TreeNode right;

* TreeNode(int x) { val = x; }

* }

*/

public class SameTree {

public boolean isSameTree(TreeNode p, TreeNode q) {

Stack<TreeNode> ss = new Stack<TreeNode>();

ss.push(p);

ss.push(q);

while(!ss.isEmpty()){

TreeNode n1 = ss.pop();

TreeNode n2 = ss.pop();

if(n1 == null && n2 == null) continue;

if(n1 == null || n2 == null) return false;

if(n1.val != n2.val) return false;

ss.push(n1.left);

ss.push(n2.left);

ss.push(n1.right);

ss.push(n2.right);

}

return true;

}

}