wknar

// edge -> not int, string, nil
// 1. get integer
// 2. if num is 0, return 0
// 3. check negative integer or not -> if negative, save -1
// 4. convert to string
// 5. create new num
// 6. multiply -1 if num is negative

func reverseInt(number: Int) -> Int? {
  if (number == 0) {

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// edge -> including nil, string, should be more than 2 for array size
// 1. get array and int
// 2. check edge case
// 3. prepare start and end index for 0 and 1
// 4. create while statement start <= end, end < n
// 5. check diff with array(start) and array(end)
// 6. if diff <= int, increase index of end
// 7. if diff >= int, increase index of start

func checkDiff(A: [Int], k: Int) -> Int {

wknar

// edge -> nil, string, max or min array size
// 1. get array and value
// 2. check edge case
// 3. check array one by one, remove element which same as value
// 4. return array.count

func getRemovedValueArray(array: [Int], value: Int) -> Int {
  var modifyArr = array
  for a in (0..<array.count).reversed() {
    if(array[a] == value) {

wknar

// edge -> nil, string, max, min
// 1. create array and init as [1]
// 2. create smallArray with adding array[n] and array[n+1]
// 2. add smallArray into bigArray
// 3. add 1 in the last

func pascal(num: Int) -> [[Int]] {
  var sumArray = [[Int]]()
  var pascalArray = [Int]()
  sumArray.append([1])

wknar

// edge -> not int, nil,  over max, min length

// 1. get and sort array to ascending
// 2. check diff with numbers in for statement ony by one

func diffK(array: [Int], k: Int) -> Int {
  var arr = array.sorted{ $0 < $1 }
  for a in 0..<arr.count {
    for b in a..<arr.count {
      if arr[b] - arr[a] == k {

wknar

// edge -> including string, inclu nil
// max and min length of array -> return value if including edge case

// 1. get array
// 2. check array one by one with for statement
// 3. if value is same as next value, delete next value
// 4. not same, add new array
// 5. return number of array and new array

func getNonDupArray(array: [Int]) -> [Int]? {

wknar

func getWrongNumber(num: Int, correct: Int) -> Int? {
  if (num == 0) {
    return nil
  }
  var array = [Int]()
  for i in 1...num {
    array.append(i)
  }
  array.remove(at: correct-1)
  return array.first

wknar

func findMajority(arr: [Int]) -> Int? {
  let sortedArray = Array(arr.sorted{ $1 < $0 })
  var maxNum = 0
  var numOfTimes = 0
  for a in sortedArray {
    if a == maxNum {
      numOfTimes += 1
    } else {
      maxNum = a
      numOfTimes = 1

wknar

func getPrice(str: String) -> Int? {
  let arr = str.components(separatedBy:"\n")
  guard let num = Int(arr[0]) else {
    return nil
  }
  if (num < 1 || num > 10) {
    return nil
  }
  print(arr)
  var priceArr = [Int]()

wknar

import Foundation

func getNumber(string: String?) -> Int? {
  // B -> 26*0 + ("B" - "A")
  // AB -> 26*1 + ("B" - "A")
  var resultNum = 0
  // unwrap optional
  guard let string = string else {
    return nil
  }