Question

This is for Java

Princess Perly has been kidnapped by the magical Hydra! The kingdom is in chaos. Now only PyPy — the bravest Knight of the country — can save the day!

Hydra is a powerful magical creature with H heads and T tails. Hydra can breathe fire from each of its heads, and can shoot poison from each of its tails. The only way to kill Hydra is to cut off all H heads and all T tails. Please note that a Hydra with 0 heads and T > 0 tails is still alive — in which case it is called a ‘Headless Hydra’.

Knight PyPy is indeed brave, but the Knight is still a novice when it comes to fighting magical creatures. Knight PyPy only know 4 moves:

• With the first move, Knight PyPy can cut off exactly one of Hydra’s heads.
• With the second move, Knight PyPy can cut off exactly one of Hydra’s tails.
• With the third move, Knight PyPy can cut off exactly two of Hydra’s heads.
• With the fourth move, Knight PyPy can cut off exactly two of Hydra’s tails.

Please remember that even though Hydra is a magical creature, the number of its heads and tails can never be negative. Thus PyPy cannot use a move when there are not enough heads or tails; e.g. PyPy cannot use the first move on a Headless Hydra.

However, Hydra is not so easy to kill. Immediately after PyPy’s move,

• If PyPy cuts off exactly one head, a new head grows immediately.
• If PyPy cuts off exactly one tail, two new tails grow immediately.
• If PyPy cuts off exactly two tails, a new head grows immediately.
• If PyPy cuts off exactly two heads, nothing happens.

Note that if after PyPy’s move Hydra has 0 heads and 0 tails, new heads and tails can still grow, in which case the Hydra is still alive.

Knight PyPy wants to kill Hydra as soon as possible, so that he can save Princess Perly. What is the minimum number of moves that PyPy needs to use to kill Hydra?

Input

Prompt for how many heads and how many tails to start the Hydra.

Output

For each hydra, allow the user to select which of the 4 moves PyPy can do. Keep track of the number of Hydra heads and tails and update the user after each attack. Keep allowing the user to attack until the Hydra is dead, or the user gives up. Allow for an option which will display S, where S is:

• If it is impossible to kill Hydra, S=−1,
• Otherwise, S is the minimum number of moves to kill Hydra.

Explanation of example

In this test case, Hydra has 3 heads and 3 tails initially. Following is a possible strategy for PyPy, with 9 moves:

• Use the fourth move. Hydra now has 4 heads and 1 tail.
• Use the third move. Hydra now has 2 heads and 1 tail.
• Use the third move. Hydra now has 0 heads and 1 tail.
• Use the second move. Hydra now has 0 heads and 2 tails.
• Use the second move. Hydra now has 0 heads and 3 tails.
• Use the second move. Hydra now has 0 heads and 4 tails.
• Use the fourth move. Hydra now has 1 head and 2 tails.
• Use the fourth move. Hydra now has 2 heads and 0 tails.
• Use the third move. Hydra now has 0 heads and 0 tails. Because PyPy cuts of exactly 2 heads, no new head nor tail grow, and Hydra is dead.

Thus PyPy can kill Hydra with 9 moves. This is also the minimum number of moves for this test case.

Answer 1

import java.util.*;

public class game
{
    static int S;
    static int head,tail;

    public static void main(String agrs[])
    {
        try
        {
        Scanner sc=new Scanner(System.in);
        int movechoice;

        System.out.println("*************Let us start the Game called Hydra Vs Knight PyPy*******************\n\n");
        System.out.println("The only way to kill Hydra is to cut off all H heads and all T tails.");

        System.out.println("Please Read Below Rules");


        System.out.println("Your Moves Are");
        System.out.println("***************************");
        System.out.println("First move ,you can cut off exactly one of Hydra’s heads.\n"+
        "Second move, you can cut off exactly one of Hydra’s tails.\n"+
        "Third move, you can cut off exactly two of Hydra’s heads.\n"+
        "Fourth move, you can cut off exactly two of Hydra’s tails.");
        System.out.println("***************************");
        System.out.println("Be Remember , you cannot use above moves when there are not enough heads or tails");


        
        System.out.println("\n\nIf you cuts off exactly one head, a new head grows immediately.");
        System.out.println("If you cuts off exactly one tail, two new tails grow immediately.");
        System.out.println("If you cuts off exactly two tails, a new head grows immediately.");
        System.out.println("If you cuts off exactly two heads, nothing happens.\n\n");
    

        //Prompt for how many heads and how many tails to start the Hydra.
        System.out.print("Choose how Many Heads to start the Hydra : ");
        head=sc.nextInt();
        System.out.print("Choose how Many Tails to start the Hydra : ");
        tail=sc.nextInt();


        while(head>0 || tail>0)
        {
            
            System.out.println("Press 1: First move ,you can cut off exactly one of Hydra’s heads.\n"+
            "Press 2: Second move, you can cut off exactly one of Hydra’s tails.\n"+
             "Press 3: Third move, you can cut off exactly two of Hydra’s heads.\n"+
             "Press 4: Fourth move, you can cut off exactly two of Hydra’s tails.\n"+
             "Press 5: For Quit !!");

            System.out.print("\nChoose Move :");

            movechoice=sc.nextInt();

            if(movechoice>0 && movechoice<6)
            {
                
                if(movechoice==5)
                {S=-1;
                 break; 
                }
                else if(movechoice==1)
                {
                    if(head>0)
                    {
                    S++;
                    }
                    else
                    {
                        System.out.println("Cannot perfomed this move , No Hydra head left!");
                    }

                }
                else if(movechoice==2)
                {
                    if(tail>0)
                    {
                    S++;
                    tail++;
                    }
                    else
                    {
                        System.out.println("Cannot perfomed this move , No Hydra tail left!");
                    }
                    
                }
                else if(movechoice==3)
                {
                    if(head>=2)
                    {
                    S++;
                    head=head-2;
                    }
                    else
                    {
                        System.out.println("Cannot perfomed this move !!");
                    }
                    
                }
            
                else 
                {
                    if(tail>1)
                    {
                    S++;
                    tail=tail-2;
                    head++;
                    }
                    else
                    {
                        System.out.println("Cannot perfomed this move , No Hydra head left!");
                    }
                    
                }

            }
            else
            {
                System.out.println("Invalid Moves");
            }
            System.out.println("\n****************\nHydra Head="+head+" Tail="+tail+" Remains\n****************\n");

        }

        if(S==-1)
        System.out.println("If it is impossible to kill Hydra!!");
        else
        {
         System.out.println("You killed hydra in "+S+" moves");
        }

    }
catch(Exception e)
{
    System.out.println("Error is "+e);
}
}
}

Output Screenshot