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257 Binary Tree Paths.swift
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257 Binary Tree Paths.swift
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//
// 257 Binary Tree Paths.swift
// LeetCode-Solutions
//
// Created by Aleksandar Dinic on 25/12/2020.
// Copyright © 2020 Aleksandar Dinic. All rights reserved.
//
import Foundation
/// Source: https://leetcode.com/problems/binary-tree-paths/
class Solution {
/// Finds all root-to-leaf paths.
///
/// - Parameter root: Binary root tree.
/// - Returns: All root-to-leaf paths.
///
/// - Complexity:
/// - time: O(n), where n is the number of nodes in the tree.
/// - space: O(n), where n is the number of nodes in the tree.
func binaryTreePaths(_ root: TreeNode?) -> [String] {
var ans = [String]()
dfs(root, path: "", ans: &ans)
return ans
}
private func dfs(_ node: TreeNode?, path: String, ans: inout [String]) {
guard let node = node else { return }
let path = "\(path)\(node.val)"
if node.left == nil, node.right == nil {
ans.append(path)
} else {
dfs(node.left, path: "\(path)->", ans: &ans)
dfs(node.right, path: "\(path)->", ans: &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
}
}