11576번 'Base Conversion'

import java.io.*;

import java.util.*;

class Main {

public static void main(String[] args) throws IOException {

BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

String[] firstLine = in.readLine().split(" ");

final int aRadix = Integer.parseInt(firstLine[0]);

final int bRadix = Integer.parseInt(firstLine[1]);

int secondLine = Integer.parseInt(in.readLine());

String[] thirdLine = in.readLine().split(" ");

int radix10Number = 0;

//10진법 변환

int power = 0;

for(int j=secondLine-1; j>=0; --j) {

int element = Integer.parseInt(thirdLine[j]);

power = power == 0 ? 1 : power * aRadix;

radix10Number += (element * power);

}

//b진법 변환

Stack<Integer> stack = new Stack<>();

while(radix10Number != 0) {

stack.push(radix10Number % bRadix);

radix10Number /= bRadix;

}

while(!stack.isEmpty()) {

int size = stack.size();

if(size == 1) {

System.out.println(stack.pop());

} else {

System.out.print(stack.pop() + " ");

}

}

}

}

간단하게 10진법 변환 후 다른 진법으로 변환해주자.

let firstLine = readLine()!.split(separator: " ").map { Int($0)! }

let aRadix = firstLine.first!

let bRadix = firstLine.last!

let secondLine = Int(readLine()!)!

let thirdLine = readLine()!.split(separator: " ").map { Int($0)! }

var radix10Number = 0

var power = 0

for i in stride(from: secondLine - 1, through: 0, by: -1) {

    let element = thirdLine[i]

    power = power == 0 ? 1 : power * aRadix

    radix10Number += (element * power)

}

var stack = [Int]()

while radix10Number != 0 {

    stack.append(radix10Number % bRadix)

    radix10Number /= bRadix

}

while !stack.isEmpty {

    print(stack.popLast()!, terminator: " ")

}

print()