Question

Using Java:

Write a program that uses hash tables and reads in a string from the command line and a dictionary of words from standard input, and checks whether it is a "good" password. Here, assume "good" means that it (i) is at least 8 characters long, (ii) is not a word in the dictionary, (iii) is not a word in the dictionary followed by a digit 0-9 (e.g., hello5), (iv) is not two words separated by a digit (e.g., hello2world).

Answer 1

import java.util.*;
import java.lang.*;
public class x{
   public static void main(String[] args) {
       //Intializing a HashTable
       Hashtable<String, Integer> h = new Hashtable<String,Integer>();
       Scanner s=new Scanner(System.in);
       System.out.println("Enter how many words to add in dictionary:");
       int dictSize=s.nextInt();
       //Filling the Dictionary
       for(int i=0;i<dictSize;i++){
           System.out.println("Enter dictionary Word:");
           String word=s.next();
           h.put(word,new Integer(1));
       }
       //Input a string
       System.out.println("Enter Password:");
       String password=s.next();
       //Check for password size
       if(password.length()<8){
           System.out.println("Not a Good Password,String length less than 8");
           System.exit(0);
       }
       //Check if password is one of dictionary word
       if(h.containsKey(password)){
           System.out.println("Not a Good Password,String present in dictionary");
           System.exit(0);
       }
       //To extract the part before digit
       String letterPart="";
       for(int i=0;i<password.length();i++){
           char as=password.charAt(i);
           if(as>='0' && as<='9'){
               letterPart=password.substring(0,i);
               //If any letter is present after number then not a good password
               if(i!=(password.length()-1)){
                   System.out.println("Not a Good Password,Digit present between words");
                   System.exit(0);
               }
           }
       }
       //Check if password is not a dictionary word followed by digit
       if(h.containsKey(letterPart)){
           System.out.println("Not a Good Password,String present in dictionary");
           System.exit(0);
       }
       System.out.println("Good Password!!");

   }
}