count_n_of_complete_binary_tree.py

def count_complete_tree():
        h = dict()  
                       
        def backtrack(node): #-> return node 의 높이. 밑에 몇개 있냐.  
            if not node.left and not node.right:
                h[node.val] = 0
                return h[node.val]
            
            left = backtrack(node.left) +1 if node.left else 0
            right = backtrack(node.right) + 1 if node.right else 0
            
            h[node.val] = left if left >= right else 0
            return h[node.val]
        
        if root:
            backtrack(root)
        else:
            return 0
        
        def is_complete(node):
            left = h[node.left.val] if node.left else 0
            right =h[node.right.val] if node.right else 0
            if  left >= right:
                return True
         
        stack = deque([root])
        cnt = 0
        while stack:
            node = stack.pop()
            if is_complete(node):
                cnt +=1
            if node.right: stack.append(node.right)
            if node.left : stack.append(node.left)
            
        
        return cnt