leetcode（java）:100 Same Tree

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