231. Lowest-Common-Ancestor-of-a-Binary-Search-Tree

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
        
        if not root:
            return None
        if root == p or root == q:
            return root
        
        leftAncestor = self.lowestCommonAncestor(root.left,p,q)
        rightAncestor = self.lowestCommonAncestor(root.right,p,q)

        if leftAncestor and rightAncestor:
            return root
        elif leftAncestor:
            return leftAncestor 
        elif rightAncestor:
            return rightAncestor
        return None


# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
        while True:
            smaller_value = min(p.val,q.val)
            larger_value = max(p.val,q.val)
            if root.val < smaller_value:
                root = root.right
            elif root.val > larger_value:
                root = root.left
            else:
                return root