问题描述

Java 代码实现

import java.math.BigInteger;
import java.util.*;

public class Main{
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		
		int n = in.nextInt();
		for (int i = 0; i < n; ++i) {
			String s = in.next();
			BigInteger temp = new BigInteger(s, 16);
			System.out.println(temp.toString(8));
		}
		
		in.close();
	}
}

import java.util.*;

public class Main{
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		
		int n = in.nextInt();
		for (int i = 0; i < n; ++i) {
			String s = in.next();
			System.out.println(binToOct(henToBin(s)));
		}

		in.close();
	}
	// 十六进制转二进制
	public static StringBuilder henToBin(String s) {
		Map<Character, String> map = new HashMap<Character, String>();
		map.put('0', "0000");map.put('1', "0001");map.put('2', "0010");map.put('3', "0011");
		map.put('4', "0100");map.put('5', "0101");map.put('6', "0110");map.put('7', "0111");
		map.put('8', "1000");map.put('9', "1001");map.put('A', "1010");map.put('B', "1011");
		map.put('C', "1100");map.put('D', "1101");map.put('E', "1110");map.put('F', "1111");
		StringBuilder sb = new StringBuilder();
		final int len = s.length();
		for (int i = 0; i < len; ++i) {
			sb.append(map.get(s.charAt(i)));
		}
		return sb;
	}
	// 二进制转八进制
	public static StringBuilder binToOct(StringBuilder s) {
		Map<String, Character> map = new HashMap<String, Character>();
		map.put("000", '0');map.put("001", '1');map.put("010", '2');map.put("011", '3');
		map.put("100", '4');map.put("101", '5');map.put("110", '6');map.put("111", '7');
		StringBuilder sb = new StringBuilder();
		int len = s.length();
		// 长度变为3的倍数，便于转换
		int temp = len % 3;
		if (temp != 0) {
			s.insert(0, temp==1?"00":"0");
			len = s.length();
		}
		// 开始转换
		for (int i = 0; i < len; i+=3) {
			sb.append(map.get(s.substring(i, i+3)));
		}
		// 去除前面的0
		len = sb.length();
		for (int i = 0; i < len; ++i) {
			if (sb.charAt(i) == '0') {
				sb.deleteCharAt(i);
			} else {
				break;
			}
		}
		return sb;
	}
}