Tree Traversal Target: 10s
Mirror check: compare left.left with right.right AND left.right with right.left. Like 'same tree' but crossed.
def isSymmetric(root):
def mirror(a, b):
if not a and not b: return True
if not a or not b: return False
return (a.val == b.val and
mirror(a.left, b.right) and
mirror(a.right, b.left))
return mirror(root.left, root.right)Type it from memory. Go.