编程题：电话号码

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☁️代码解析

import java.util.*;
import java.io.*;
public class Main
{
public static void main(String[] args) throws Exception
{
//建立映射
//字母--->数字
HashMap<Character, Character> mp = new HashMap<>();
String alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
String num = "22233344455566677778889999";
char[] alphaArr = alpha.toCharArray();
char[] numArr = num.toCharArray();
for(int i = 0; i < alphaArr.length; ++i)
{
mp.put(alphaArr[i], numArr[i]);
}
//用set保存结果，去重
TreeSet<String> set = new TreeSet<>();
String line;
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
while((line = reader.readLine()) != null)
{
set.clear();

int n = Integer.parseInt(line);
//处理n个字符串
for(int i = 0; i < n; ++i)
{
line = reader.readLine();
//保存转换之后的字符串
StringBuilder sb = new StringBuilder();
char[] arr = line.toCharArray();
//处理每一个字符
for(char ch : arr)
{
if(isDigit(ch))
sb.append(ch);
else if(isUpper(ch))
sb.append(mp.get(ch));
}
//调整格式：xxx-xxxx
line = sb.substring(0, 3) + "-" + sb.substring(3);
//保存结果
set.add(line);
}
//打印转换之后的结果
for(String str : set)
System.out.println(str);
//每组数据用空行隔开
System.out.println();
}
}
public static boolean isDigit(char ch)
{
return '0' <= ch && ch <= '9';
}
public static boolean isUpper(char ch)
{
return 'A' <= ch && ch <= 'Z';
}