[프로그래머스] 3진법 뒤집기(Swift)

import Foundation

func solution(_ n:Int) -> Int {

    var num = n
    var sum = 0
    var digit = 1
    var arr = [Int]()

    while (num > 0) {
        arr.append(num % 3)

        num /= 3
    }


    for n in arr.reversed() {
        sum += n * digit
        digit *= 3
    }

    return sum
}

import Foundation

  func solution(_ n:Int) -> Int {
        let flipToThree = String(n,radix: 3)
        let answer = Int(String(flipToThree.reversed()),radix:3)!
        return answer

	}

---

진수 변환

10진수 -> 2진수 (Int -> String)

var value = 100
var result = ""

result = String(value, radix: 2)

print(result) // 1100100

2진수 -> 10진수 (String -> String)

var value = "1100100"
var result: Int = Int(value, radix: 2)!

print(result) // 100

2진수 -> 16진수

var value = "1100100"
var result: Int = Int(value, radix: 2)!

var newResult: String = String(result, radix: 16)

print(newResult)	// c9

2진수 -> 10진수 -> 16진수