spurscho

class TreeNode {
    var data: Int
    var left: TreeNode?
    var right: TreeNode?
    var parent: TreeNode?

    init(_ data: Int) {
        self.data = data

spurscho

public class BinaryNode<Element> {
    public var value: Element // 노드의 값
    public var leftChild: BinaryNode? // 왼쪽 노드 (옵셔널)
    public var rightChild: BinaryNode? // 오른쪽 노드 (옵셔널)
    public init(value: Element) { self.value = value } // 초기화 함수

    public func traverseInOrder(visit: (Element) -> Void) {
        leftChild?.traverseInOrder(visit: visit)
        visit(value)
        rightChild?.traverseInOrder(visit: visit)

spurscho

class Solution {
    
    func combinationSum(_ candidates: [Int], _ target: Int) -> [[Int]] {
    
        var res = [[Int]]()
        var temp = [Int]()
        helper(&res, &temp, candidates, 0, target)
        return res
    }
    

spurscho

class Solution {
    func isValidSudoku(_ board: [[Character]]) -> Bool {
        var rowSet = [Set<Character>](repeating: Set<Character>(), count: 9)
        var colSet = [Set<Character>](repeating: Set<Character>(), count: 9)
        var squareSet = [Set<Character>](repeating: Set<Character>(), count: 9)

        for (rowIndex, row) in board.enumerated() {
            for (colIndex, character) in row.enumerated() {
                if character == Character(".") {
                    continue

spurscho

class Solution {
    func countAndSay(_ n: Int) -> String {
        if n == 1 { return "1" }
        let val = countAndSay( n - 1 )
        let res = "\(count(String(val)))"
        return res
    }
    
    func count(_ str: String) -> String {
        guard str.count > 0 else {

spurscho

public struct Stack<T> {
    private var elements = Array<T>()
    public init() {}
    
    public mutating func pop() -> T? {
        return self.elements.popLast()
    }
    
    public mutating func push(element: T) {
        self.elements.append(element)

spurscho

public struct Queue<T> {
    internal var data = Array<T>()
    public init() {}
    
    public mutating func dequeue() -> T? {
        return data.removeFirst()
    }
    
    public func peek() -> T? {
        return data.first

spurscho

class Solution { // my code got timelimted error. this is new codes
    func strStr(_ haystack: String, _ needle: String) -> Int {
        guard !needle.isEmpty else { return 0 }
        guard haystack.count >= needle.count else { return -1 }
        
        let distance = haystack.count - needle.count
        for i in 0...distance {
            let start = haystack.index(haystack.startIndex, offsetBy: i)
            let end = haystack.index(haystack.startIndex, offsetBy: i+needle.count)
            

spurscho

class Solution {
    func removeElement(_ nums: inout [Int], _ val: Int) -> Int {
        guard nums.count > 0 else {
            return 0
        }
        
        var idx: Int = 0
        while true {
            if idx == nums.count {
                break

spurscho

class Solution {
    func removeDuplicates(_ nums: inout [Int]) -> Int {
        guard nums.count > 0 else {
            return 0
        }
        
        nums.sort()
        var idx: Int = 0
        while true {
            if idx + 1 == nums.count {