[백준 1373] 2진수8진수<Java>

import java.util.Scanner;

public class 이진수8진수 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		int sum=0;
		int len=s.length();
//		int num=0;
//		for(int i=0;i<s.length();i++) {
//			num+=(s.charAt(i)-'0')*(int)(Math.pow(2, s.length()-i-1));
//		}
//		System.out.println(Long.toOctalString(num));
		if(s.length()%3==2) {
			s="0"+s;//3의 배수로
			len++;
		}
		else if(s.length()%3==1) {
			s="00"+s;
			len=len+2;
		}
		StringBuilder sb = new StringBuilder();
		int cnt=2;
		for(int i=0;i<len;i++) {
			sum += (int) (Math.pow(2, cnt)*(s.charAt(i)-'0'));
			cnt--;
			if(cnt==-1) {
				sb.append(sum);
				sum=0;
				cnt=2;
			}
		}
		System.out.println(sb);
	}
}