129. 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.

Note: A leaf is a node with no children.

Example:

Input: [1,2,3]
    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:

Input: [4,9,0,5,1]
    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.

# @lc code=start
using LeetCode
using DataStructures

function sum_numbers(root::TreeNode)::Int
    queue, res = Deque{TreeNode}(), 0

    !isnothing(root) && push!(queue, root)

    while !isempty(queue)
        node = popfirst!(queue)
        if isnothing(node.left) && isnothing(node.right)
            res += node.val
        end
        if !isnothing(node.left)
            node.left.val += node.val * 10
            push!(queue, node.left)
        end
        if !isnothing(node.right)
            node.right.val += node.val * 10
            push!(queue, node.right)
        end
    end

    return res
end
# @lc code=end

sum_numbers (generic function with 1 method)

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