블루 브리지 컵 베이스-016 - HexadecimalTo_Octal

제목의 뜻
n (행) 입력
16진수 문자열 n 개 입력 & & 1 <= hexchs.lehgth<=10000-> 16^(10000-1)-근사 > 16^10000-> 2^40000>> 2^31(int) or 2^63(long)-> 중간수는 정형->char[]
행당 8진수 문자열 1개 내보내기
(16진수 = 4bits, 8진수 = 3bits -> 중간 수에서 binary chs 추출)
코드

import java.awt.AlphaComposite;
import java.util.Scanner;

public class Main {

	static char[] HexAlphabet = {'0','1','2','3','4',
				     '5','6','7','8','9',
				     'A','B','C','D','E','F'
								 };
	static String[] HexBin = {  "0000","0001","0010","0011",
				    "0100","0101","0110","0111",
				    "1000","1001","1010","1011",
				    "1100","1101","1110","1111",
							};
	static char[][] OctBin = {  {'0','0','0'},{'0','0','1'},{'0','1','0'},{'0','1','1'},
				    {'1','0','0'},{'1','0','1'},{'1','1','0'},{'1','1','1'},
							};
	public static void main(String[] args) {

		
		Scanner keyin = new Scanner(System.in);
		int n = keyin.nextInt();
		while (n-- > 0) {
			String hex_str = keyin.next();
			char[] hex_chs = hex_str.toCharArray();
			char[] bin_chs = hexChsToBinaryChs(hex_chs);
			char[] oct_chs = binChsToOctalChs(bin_chs);
			System.out.println(String.valueOf(oct_chs));
		}
	}
	public static int chsSearch(char[] target){
		for (int i = 0; i < OctBin.length; i++) {
			int j;
			for (j = 0; j < target.length; j++) {
				if( OctBin[i][j] != target[j] )
					break;
			}
			if(j == target.length)
				return i;
		}
		return -1;
	}
	public static char[] binChsToOctalChs(char[] bin_chs){
		if( bin_chs.length % 3 >= 1){
			bin_chs = ("0"+String.valueOf(bin_chs)).toCharArray();
			if( bin_chs.length % 3 == 2){
				bin_chs = ("0"+String.valueOf(bin_chs)).toCharArray();
			}
		}
		char[] oct_chs = new char[bin_chs.length/3];
		for (int i = bin_chs.length - 3; i >= 0 ; i -= 3) {
			char[] oct_section = { bin_chs[i],bin_chs[i+1],bin_chs[i+2] };
			int sub_oct_digit = chsSearch(oct_section);
			oct_chs[i/3] = HexAlphabet[sub_oct_digit];
		}
		int cnt_head_zero = 0;
		while(oct_chs[cnt_head_zero] == '0'){
			cnt_head_zero++;
		} 
		char[] erase_head_zero_oct_chs = new char[ oct_chs.length - cnt_head_zero];
		for (int i = 0; i < erase_head_zero_oct_chs.length; i++) {
			erase_head_zero_oct_chs[i] = oct_chs[i + cnt_head_zero];
		}
		return erase_head_zero_oct_chs;
	}
	public static char[] hexChsToBinaryChs(char[] hex_chs){
		char[] bin_chs = new char[hex_chs.length*4];
		for (int i = bin_chs.length - 4; i >= 0; i -= 4) {
			int sub_hex = binSearch(HexAlphabet, hex_chs[i/4]);
			System.arraycopy(HexBin[sub_hex].toCharArray(), 0,bin_chs, i , 4);
		}
		return bin_chs;
	}

	public static int binSearch(char[] src,char target){
		int low = 0,high = src.length - 1,mid = 0;
		do {
			mid = (low + high)/2;
			if(target == src[mid]) 
				return mid;
			else if(target > src[mid])
				low = mid + 1;
			else
				high = mid - 1;
		} while (low <= high);
		return -1;
	}
}

Summary
[두 바퀴 두 서치 돌고 제로로 이동!]
i) 2 Search 2회전 -> binSearch
  hex_chs+구조 HexAlphabet 대조표(HexAlphabet과 OctalAlphabet 부분은 통용할 수 있음) + HexBin-> HexChsToBinaryChs에 사용
  bin_chs+HexAlphabet+HexBin->binchsToOctalChs용
ii) 제로 가기
binchsToOctalCh에서 binchs -> oct_chs 이후
iii) 출력 ->sysout {String.value Of(octal chs)}