129. Sum Root to Leaf Numbers

129. Sum Root to Leaf Numbers

题目:
https://leetcode.com/problems/sum-root-to-leaf-numbers/

难度:

Medium

其实递归不难想到，不过我自己做错在细节方面

如果只有单支，每朝下走一层，代表的数字都增加10， 10* 原本的 + 新节点的数字，最终也是用这个来解

class Solution(object):
    def sumNumbers(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        return self.calSum(root,0)
    
    
    def calSum(self,root,curSum):
        if root == None:
            return 0
        else:
            curSum = curSum * 10 + root.val
            if root.left == None and root.right == None:
                return curSum
            else:
                return self.calSum(root.left, curSum) + self.calSum(root.right, curSum)