[Solved] You are given the root of a binary tree containing digits from 0 to 9 only. Each root-to-leaf path in the tree represents a number.

Table of Contents

Question

You are given the root of a binary tree containing digits from 0 to 9 only.

Each root-to-leaf path in the tree represents a number.

  • For example, the root-to-leaf path 1 -> 2 -> 3 represents the number 123.

Return the total sum of all root-to-leaf numbers. Test cases are generated so that the answer will fit in a 32-bit integer.

leaf node is a node with no children.

Example 1:

num1tree
Input: root = [1,2,3]
Output: 25
Explanation:
The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.
Therefore, sum = 12 + 13 = 25.

Example 2:

num2tree
Input: root = [4,9,0,5,1]
Output: 1026
Explanation:
The root-to-leaf path 4->9->5 represents the number 495.
The root-to-leaf path 4->9->1 represents the number 491.
The root-to-leaf path 4->0 represents the number 40.
Therefore, sum = 495 + 491 + 40 = 1026.

Constraints:

  • The number of nodes in the tree is in the range [1, 1000].
  • 0 <= Node.val <= 9
  • The depth of the tree will not exceed 10.

Python Solution

def traverse(root,l,prev):
    if root==None:return
    if root.left==None and root.right==None:
        l.append(int(prev+str(root.val)))
    traverse(root.left,l,prev+str(root.val))
    traverse(root.right,l,prev+str(root.val))

class Solution:
    def sumNumbers(self, root: TreeNode) -> int:
        l = []
        traverse(root,l,'')
        return sum(l)
Abhishek Sharma
Abhishek Sharma

Started my Data Science journey in my 2nd year of college and since then continuously into it because of the magical powers of ML and continuously doing projects in almost every domain of AI like ML, DL, CV, NLP.

Articles: 520

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