Leetcode 101. Symmetric Tree

https://leetcode.com/problems/symmetric-tree/

Use recursion.

Solution:

# T:O(n) S:O(h)
class Solution:
    # @param root, a tree node
    # @return a boolean
    def help(self, p, q):
        if p == None and q == None: return True
        if p and q and p.val == q.val:
            return self.help(p.right, q.left) and\
      self.help(p.left, q.right)
        return False
    
    def isSymmetric(self, root):
        if root:
            return self.help(root.left, root.right)
        return True

Run Time: 72 ms