1644. Lowest Common Ancestor of a Binary Tree II

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LCA problem

# 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':

        self.node = None


        def dfs(node, p , q):
            if not node:
                return 0

            left = dfs(node.left, p, q)
            right = dfs(node.right, p, q)
            current = 1 if node == p or node == q else 0

            if not self.node and left + right + current == 2:
                self.node = node
            
            return left+right+current

        


        dfs(root, p, q)


        return self.node