Question

IN JAVA!! THANK YOU

Assignment Overview

You are to include both of these recursive assignments in your code submission. Remember to well-document your code and submit your code and output as text file. All the methods are static and to be included in a class named Recursives, so that a test program can directly call these methods via the class name without creating objects of the class. In addition, write a test program (within Main) to test these recursive methods.

1 Divide and Conquer

A detachment of n soldiers must cross a wide and deep river with no bridge in sight. They noticed two boys playing in a rowboat by the shore. The boat is so tiny, however, that it can only hold two boys or one soldier. How can the soldiers get across the river and leave the boys in joint possession of the boat? Write a recursive method to solve the problem with this header:

public static void crossRiver ( int n )

Your output should look like this for two soldiers:

--------------------------------------------------

2 soldiers ----> 0 soldiers, 2 boys

2 soldiers, 1 boy <---- 0 soldiers, 1 boy

1 soldier, 1 boy ----> 1 soldier, 1 boy

1 soldier, 2 boys <---- 1 soldier

--------------------------------------------------

1 soldier ----> 1 soldier, 2 boys

1 soldier, 1 boy <---- 1 soldier, 1 boy

0 soldiers, 1 boy ----> 2 soldiers, 1 boy

0 soldiers, 2 boys <---- 2 soldiers

--------------------------------------------------

Test your implementation with n = 2; 3; 4; 5 soldiers.

Hint: To show the process, you need to write another method to display how one solider crosses the river

2 Binary Conversion

Write a method that takes a positive integer n as a parameter and returns its binary representation as String. Write a recursive method to solve the problem with this header: 1 public static String integerToBinary (int n ) Hint: repeatedly divide 2 into n and read the remainders backwards. Test your implementation with n = 1; 11; 47; 483648.

Answer 1

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// Java Code

public class RecursiveMethods {

   public static String getSoldierString(int s){
       if(s == 1){
           return "soldier";
       }else{
           return "soldiers";
       }
   }
  
   public static void crossRiver(int sLeft, int sRight){
       String sLeftSoldier, sRightSoldier;
      
       if(sLeft == 0){
           return;
       }
      
       sLeftSoldier = getSoldierString(sLeft);
       sRightSoldier = getSoldierString(sRight);
       System.out.println("--------------------------------------------------");
      
       System.out.println(sLeft + " " + sLeftSoldier + " ----> "+ sRight + " " + sRightSoldier+", 2 boys");
       System.out.println(sLeft + " " + sLeftSoldier + ",1 boy <---- "+ sRight + " " + sRightSoldier + ", 1 boy");
       sRight = sRight + 1;
       sLeft = sLeft - 1 ;
       sLeftSoldier = getSoldierString(sLeft);
       sRightSoldier = getSoldierString(sRight);
       System.out.println(sLeft + " "+ sLeftSoldier + ",1 boy ----> "+ sRight +" " + sRightSoldier + ", 1 boy");
       System.out.println(sLeft + " "+ sLeftSoldier + ",2 boys <---- "+ sRight + " " + sRightSoldier);
      
      
       crossRiver(sLeft,sRight);
      
   }
  
   public static String integerToBinary(int n){
       if(n == 0){
           return "0";
       }else if(n == 1){
           return "1";
       }else{
           String rem;
           if(n%2 == 0){
               rem = "0";
           }else {
               rem = "1";
           }
           return integerToBinary(n/2) + rem;
       }
      
   }
  
  
   public static void main(String[] args) {
       // TODO Auto-generated method stub
       int n = 2;
       System.out.println("\nRiver crossing for "+n +" soldiers below : ");
       crossRiver(n,0);
       n = 3;
       System.out.println("\nRiver crossing for "+n +" soldiers below : ");
       crossRiver(n,0);
       n= 4;
       System.out.println("\nRiver crossing for "+n +" soldiers below : ");
       crossRiver(n,0);
       System.out.println("--------------------------------------------------");
       System.out.println();
       n = 1;
       System.out.println("Binary representation of " + n + " is "+ integerToBinary(n));
       n = 11;
       System.out.println("Binary representation of " + n + " is "+ integerToBinary(n));
       n = 47;
       System.out.println("Binary representation of " + n + " is "+ integerToBinary(n));
       n = 483648;
       System.out.println("Binary representation of " + n + " is "+ integerToBinary(n));
      
   }

}

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// output for the above