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  • LeetCode-129. Sum Root to Leaf Numbers

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

    Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.

    An example is the root-to-leaf path 1->2->3 which represents the number 123.

    Find the total sum of all root-to-leaf numbers.

    For example,

        1
       / 
      2   3
    

    The root-to-leaf path 1->2 represents the number 12.
    The root-to-leaf path 1->3 represents the number 13.

    Return the sum = 12 + 13 = 25.

    Solutions

    # Definition for a binary tree node.
    # class TreeNode(object):
    #     def __init__(self, x):
    #         self.val = x
    #         self.left = None
    #         self.right = None
    
    class Solution(object):
        def sumNumbers(self, root):
            """
            :type root: TreeNode
            :rtype: int
            """
            return self.Sum(root, 0)
        def Sum(self, node, s):
            if not node:
                return 0
            if not node.left and not node.right:
                return s*10 + node.val
            return self.Sum(node.left, s*10 + node.val) + self.Sum(node.right, s*10 + node.val)
    
    # Definition for a binary tree node.
    # class TreeNode(object):
    #     def __init__(self, x):
    #         self.val = x
    #         self.left = None
    #         self.right = None
    
    class Solution(object):
        def sumNumbers(self, root):
            """
            :type root: TreeNode
            :rtype: int
            """
            if not root:
                return 0
            stack, res = [(root, root.val)], 0
            while stack:
                node, val = stack.pop()
                if not node.left and not node.right:
                    res += val
                if node.right:
                    stack.append((node.right, val*10 + node.right.val))
                if node.left:
                    stack.append((node.left, val*10 + node.left.val))
            return res
    
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  • 原文地址:https://www.cnblogs.com/binwone/p/6051421.html
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