Lc236. nearest common ancestor of binary tree

def lowestCommonAncestor(self, root, p, q):
        """ :type root: TreeNode :type p: TreeNode :type q: TreeNode :rtype: TreeNode """
        def recur(root,p,q):
            if not root:
                return 
            if root.val == p.val or root.val == q.val:  # Put it here , After finding a subtree with this node as the root node, there is no need to access it . because ：
                return root                             # situation 1 ：  The other value is on the subtree of the currently found node , The current node is the answer 
            left = recur(root.left,p,q)                 # situation 2 ：  Another value is not on the subtree of the current node , Then the subtree of the current node can be found elsewhere without access 
            right = recur(root.right,p,q)
            if left and right:                          # Put it in the following position , The result information can be passed forward through the return value  
                return root
            return left if left else right               
        return recur(root,p,q)