Telephone.java

package com.ub.sol;

import java.util.ArrayList;
import java.util.List;

public class Telephone {

	private char[][] dict = {{'0'},
			{'1'},
			{'a','b','c'},
			{'d','e','f'},
			{'g','h','i'},
			{'j','k','l'},
			{'m','n','o'},
			{'p','q','r','s'},
			{'t','u','v','w'},
			{'w','x','y','z'}
	};

	public Telephone() {

	}

	private void  recPermute(String input,String result,List<String> output) {

		
		//		for(int i=0;i<input.length();i++) {
		//			output.add((dict[currentChar][i]));
		//		}
		if(input.length() == 0) {
			output.add(result);
//			System.out.println("" + result);
		}else {
			int currentChar = input.charAt(0) - 48 ;
//			System.out.println(currentChar);
//			result += result;
			String remainderString = input.substring(1);
			for(int i=0;i<dict[currentChar].length;i++) {
				if(i==0) {
				result += (Character.toString(dict[currentChar][i]));
				}else {
				 String temp = result.substring(0,result.length()-1);
				 temp += (Character.toString(dict[currentChar][i]));
				 result = temp;
				}
				recPermute(remainderString,result,output);
			}
		
		}

	}



	public static void main(String args[]) {
		Telephone tel = new Telephone();
		for (int i=0;i<9;i++) {
			//			System.out.println(""+tel.dict[i].length);
		}
		String c = "abc".substring(2,3);
		//	     System.out.println(""+c);
		List<String> strList = new ArrayList<String>();
		tel.recPermute("415520","" ,strList);
		System.out.println("size :"+strList.size());
	}

}