leetcode same tree

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

很简单的一道题，不过当时写的代码挺蠢的，学习了一个别人的，感觉比较简洁。

public boolean isSameTree(TreeNode p, TreeNode q) {
    if (p == null & q == null)
        return true;
    else if (p == null || q == null)
        return false;
    else return p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
}