题目：

题解：

class Solution {public boolean isSameTree(TreeNode p, TreeNode q) {if (p == null && q == null) {return true;} else if (p == null || q == null) {return false;}Queue<TreeNode> queue1 = new LinkedList<TreeNode>();Queue<TreeNode> queue2 = new LinkedList<TreeNode>();queue1.offer(p);queue2.offer(q);while (!queue1.isEmpty() && !queue2.isEmpty()) {TreeNode node1 = queue1.poll();TreeNode node2 = queue2.poll();if (node1.val != node2.val) {return false;}TreeNode left1 = node1.left, right1 = node1.right, left2 = node2.left, right2 = node2.right;if (left1 == null ^ left2 == null) {return false;}if (right1 == null ^ right2 == null) {return false;}if (left1 != null) {queue1.offer(left1);}if (right1 != null) {queue1.offer(right1);}if (left2 != null) {queue2.offer(left2);}if (right2 != null) {queue2.offer(right2);}}return queue1.isEmpty() && queue2.isEmpty();}
}