package com.example.baseconverter;

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class BaseConverter {

    // 字符到数值的映射
    private static final Map<Character, Integer> charToValueMap = new HashMap<>();
    // 数值到字符的映射
    private static final Map<Integer, Character> valueToCharMap = new HashMap<>();

    static {
        // 初始化字符到数值的映射
        for (char c = '0'; c <= '9'; c++) {
            charToValueMap.put(c, c - '0');
        }
        for (char c = 'A'; c <= 'F'; c++) {
            charToValueMap.put(c, c - 'A' + 10);
        }

        // 初始化数值到字符的映射
        for (int i = 0; i <= 9; i++) {
            valueToCharMap.put(i, (char) ('0' + i));
        }
        for (int i = 10; i <= 15; i++) {
            valueToCharMap.put(i, (char) ('A' + i - 10));
        }
    }

    // 将任意进制的数转换为十进制
    public static int toDecimal(String number, int base) {
        int decimalValue = 0;
        int power = 0;

        for (int i = number.length() - 1; i >= 0; i--) {
            char digit = number.charAt(i);
            int value = charToValueMap.get(digit);
            decimalValue += value * Math.pow(base, power);
            power++;
        }

        return decimalValue;
    }

    // 将十进制数转换为任意进制
    public static String fromDecimal(int decimalValue, int base) {
        if (decimalValue == 0) {
            return "0";
        }

        StringBuilder result = new StringBuilder();
        while (decimalValue > 0) {
            int remainder = decimalValue % base;
            result.insert(0, valueToCharMap.get(remainder));
            decimalValue /= base;
        }

        return result.toString();
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // 输入原始进制和数
        System.out.print("请输入原始进制 (2-16): ");
        int sourceBase = scanner.nextInt();
        System.out.print("请输入原始数: ");
        String sourceNumber = scanner.next();

        // 输入目标进制
        System.out.print("请输入目标进制 (2-16): ");
        int targetBase = scanner.nextInt();

        // 验证输入
        if (sourceBase < 2 || sourceBase > 16 || targetBase < 2 || targetBase > 16) {
            System.out.println("进制必须在2到16之间！");
            return;
        }

        // 转换
        int decimalValue = toDecimal(sourceNumber, sourceBase);
        String targetNumber = fromDecimal(decimalValue, targetBase);

        // 输出结果
        System.out.println("转换后的数是: " + targetNumber);
    }
}