求根节点到叶节点数字之和

class TreeNode:
    def __init__(____):
        self.val = val
        self.left = left
        self.right = right

def solve():
    def sumNumbers(____):
        def dfs(____):
            if not node:
                return ____
            curr = curr * ____ + node.val
            if not node.left and not node.right:
                return curr
            return dfs(____) + dfs(____)
        return dfs(____)
    root = TreeNode(____, TreeNode(____), TreeNode(____))
    print(sumNumbers(____))