不错这个数据很有帮助，贴一下我的ac代码：
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;

public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		// long start = System.currentTimeMillis();
		int n = Integer.parseInt(br.readLine());
		HashMap<String, Integer> count = new HashMap<String, Integer>(n);
		for (int i = 0; i < n; i++) {
			char[] s = br.readLine().toCharArray();
			StringBuilder sb = new StringBuilder();
			for (int j = 0; j < s.length; j++) {
				if (s[j] == '-') {
					continue;
				}
				switch (s[j]) {
				case 'A':
				case 'B':
				case 'C':
					sb.append('2');
					break;
				case 'D':
				case 'E':
				case 'F':
					sb.append('3');
					break;
				case 'G':
				case 'H':
				case 'I':
					sb.append('4');
					break;
				case 'J':
				case 'K':
				case 'L':
					sb.append('5');
					break;
				case 'M':
				case 'N':
				case 'O':
					sb.append('6');
					break;
				case 'P':
				case 'R':
				case 'S':
					sb.append('7');
					break;
				case 'T':
				case 'U':
				case 'V':
					sb.append('8');
					break;
				case 'W':
				case 'X':
				case 'Y':
					sb.append('9');
					break;
				default:
					sb.append(s[j]);
					break;
				}
			}
			String ss = sb.toString();
			if (count.containsKey(ss)) {
				count.put(ss, count.get(ss) + 1);
			} else {
				count.put(ss, 1);
			}
		}
		// long end = System.currentTimeMillis();
		// System.out.println(end - start);
		ArrayList<String> res = new ArrayList<String>();
		for (String key : count.keySet()) {
			if (count.get(key) > 1) {
				res.add(key);
			}
		}
		if (res.isEmpty()) {
			System.out.println("No duplicates.");
			return;
		}
		// System.out.println(System.currentTimeMillis() - start);
		Collections.sort(res);
		for (String s : res) {
			System.out.println(s.substring(0, 3) + "-" + s.substring(3) + " " + count.get(s));
		}
		// System.out.println(System.currentTimeMillis() - start);
	}
}