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1022 Sum of Root To Leaf Binary Numbers.swift
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1022 Sum of Root To Leaf Binary Numbers.swift
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//
// 1022 Sum of Root To Leaf Binary Numbers.swift
// LeetCode-Solutions
//
// Created by Aleksandar Dinic on 08/09/2020.
// Copyright 漏 2020 Aleksandar Dinic. All rights reserved.
//
import Foundation
/// Source: https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers/
class Solution {
/// Calculates the sum where the numbers are represented by the path from the root to
/// the leaf.
///
/// - Parameter root: Binary tree root.
/// - Returns: The sum.
///
/// - Complexity:
/// - time: O(n), where n is the number of nodes in the binary tree.
/// - space: O(n), where n is the number of nodes in the binary tree.
func sumRootToLeaf(_ root: TreeNode?) -> Int {
guard let root = root else { return 0 }
var ans = 0
dfs(root, root.val, &ans)
return ans
}
private func dfs(_ root: TreeNode, _ currNumber: Int, _ ans: inout Int) {
if root.left == nil, root.right == nil {
ans += currNumber
return
}
if let left = root.left {
dfs(left, (currNumber * 2) + left.val, &ans)
}
if let right = root.right {
dfs(right, (currNumber * 2) + right.val, &ans)
}
}
}
/// Provided code
public class TreeNode {
public var val: Int
public var left: TreeNode?
public var right: TreeNode?
public init() {
self.val = 0
self.left = nil
self.right = nil
}
public init(_ val: Int) {
self.val = val
self.left = nil
self.right = nil
}
public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
self.val = val
self.left = left
self.right = right
}
}