> 用了二叉排序树
> 
> 结点只写了4个变量和一个构造器，不敢写什么方法了，开销这么大!
> 
> 输出部分不是很好，用了多个模除才输出一个电话号码
> 
> 代码如下，如果谁有兴趣看的话，请指出可以改进的地方，谢谢~~~:)
> 
> //Problem 1002
> import java.io.BufferedReader;
> import java.io.InputStreamReader;
> import java.io.IOException;
> 
> class Phone {
> 	int num, times;
> 	Phone left, right;
> 	public Phone(int val) {
> 		num = val;
> 		times = 1;
> 		left = right = null;
> 	}
> }
> 
> public class Main {
> 	
> 	private final static char[] table =
> //		  A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,
> 		{'2','2','2','3','3','3','4','4','4','5','5','5','6','6','6',
> //		 P, ,R,S,T,U,V,W,X,Y
> 		 '7','7','7','7','8','8','8','9','9','9'};
> 	private static char[] output = {'0','0','0','-','0','0','0','0'};
> 	private static boolean noDuplicates = true;
> 	
>          //插入新电话号码到二叉排序树
> 	public static void add(Phone tree, Phone newPhone) {
> 		if(newPhone.num<tree.num) {
> 			if(tree.left!=null) add(tree.left,newPhone);
> 			else tree.left = newPhone;
> 		}else if(newPhone.num>tree.num) {
> 			if(tree.right!=null) add(tree.right,newPhone);
> 			else tree.right = newPhone;
> 		}else {
> 			tree.times++;
> 		}
> 	}
> 	
>          //中序遍历二叉排序树
> 	public static void midtraval(Phone tree) {
> 		if(tree!=null) {
> 			if(tree.left!=null) midtraval(tree.left);
> 			if(tree.times>1) {
> 				noDuplicates = false;
> 				for(int i=7; i>=0; i--) {
> 					if(i==3) continue;
> 					output[i] = (char)(tree.num%10+48);
> 					tree.num /= 10;
> 				}
> 				System.out.print(output);
> 				System.out.println(" " + tree.times);
> 			}
> 			if(tree.right!=null) midtraval(tree.right);
> 		}
> 	}
> 	
> 	public static void main(String[] args) throws IOException {
> 		BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
> 		int numbers = Integer.parseInt(stdin.readLine());
> 		int length, delta, i, k;
> 		Phone root = null;
> 		char[] num = {'0','0','0','0','0','0','0'};
> 		while(numbers!=0) {
> 			String s = stdin.readLine();
> 			length = s.length();
> 			for(i=length-1, k=6; i>=0; i--) {
> 				delta = s.charAt(i) - 'A';
> 				if(delta>=0) {
> 					num[k--] = table[delta];
> 				}else if(delta!=-20) {
> 					num[k--] = s.charAt(i);
> 				}
> 			}
> 			if(root==null) root = new Phone(Integer.parseInt(new String(num)));
> 			else {
> 				Phone newPhone = new Phone(Integer.parseInt(new String(num)));
> 				add(root,newPhone);
> 			}
> 			numbers--;
> 		}
> 		midtraval(root);
> 		if(noDuplicates) System.out.println("No duplicates.");
> 	}
> }///:~