> import java.util.*;
> 
> public class Main
> {
>     public static void main(String[] args)
>     {
>         Scanner scan = new Scanner(System.in);
>         int num = scan.nextInt();
>         int flag = 0;
>         int i;
>         ArrayList<String> strArray = new ArrayList<String>();
>         ArrayList<String> strArray1 = new ArrayList<String>();
>         String str = scan.nextLine();
>         String s;
>         for(i = 1; i <= num; i++) {
>         	str = scan.nextLine();
>         	s = change(str);
>         	strArray.add(s);
>         }
>         while(!strArray.isEmpty()) {
>         	String s1 = (String)strArray.get(0);
>         	int count = 0;
>         	Iterator<String> iter = strArray.iterator();
>         	String element;
>         	while(iter.hasNext()) {
>         		element = iter.next();
>         		if(s1.equals(element)) {
>         			count++;
>                 	iter.remove();
>         		}
>         	}
>         	if(count > 1) {
>             	StringBuilder sb = new StringBuilder(s1);
>             	sb.append(" "+count);
>             	strArray1.add(sb.toString());
>         	}
>         	else
>         		flag++;
>         }
>         if(flag == num)
>         	System.out.println("No duplicates.");
>         else {
>             Collections.sort(strArray1);  
>             for(String element : strArray1)
>             	System.out.println(element);
>         }
>         scan.close();
>     }
>     
>     public static String change(String str) {
>     	str = str.replace("-", "");
>     	for(int i = 0; i < str.length(); i++) {
>     		if(str.charAt(i) == 'A' || str.charAt(i) == 'B' || str.charAt(i) == 'C')
>     			str = str.replace(str.charAt(i), '2');
>     		if(str.charAt(i) == 'D' || str.charAt(i) == 'E' || str.charAt(i) == 'F')
>     			str = str.replace(str.charAt(i), '3');
>     		if(str.charAt(i) == 'G' || str.charAt(i) == 'H' || str.charAt(i) == 'I')
>     			str = str.replace(str.charAt(i), '4');
>     		if(str.charAt(i) == 'J' || str.charAt(i) == 'K' || str.charAt(i) == 'L')
>     			str = str.replace(str.charAt(i), '5');
>     		if(str.charAt(i) == 'M' || str.charAt(i) == 'N' || str.charAt(i) == 'O')
>     			str = str.replace(str.charAt(i), '6');
>     		if(str.charAt(i) == 'P' || str.charAt(i) == 'R' || str.charAt(i) == 'S')
>     			str = str.replace(str.charAt(i), '7');
>     		if(str.charAt(i) == 'T' || str.charAt(i) == 'U' || str.charAt(i) == 'V')
>     			str = str.replace(str.charAt(i), '8');
>     		if(str.charAt(i) == 'W' || str.charAt(i) == 'X' || str.charAt(i) == 'Y')
>     			str = str.replace(str.charAt(i), '9');
>     	}
>     	StringBuilder sb = new StringBuilder(str);
>     	sb.insert(3, "-");
>     	return sb.toString();
>     }
> }


1数据储在treemap里，可以省下单独对数组排序的开销，因为它是会主动维护key的顺序的；
2change函数里，字符串的replace方法开销确实很大。