Question

create an input file with the numbers shown below and then create an output file with java ?

Polish Peasant Multiplication

About

It takes two numbers, side by side. The left number is multiplied by 2 every time the right number is divided by 2.

50                    30

100                  15

200                  7

400                  3

800                  1

Take out the numbers in the left side that corresponds to an even number to the right side, in this case 30 is the only even number available.

                        

30

100                  15

200                  7

400                  3

800                  1

Add all the left side: This will equal to 1500.

Test the answer by multiplying the first two original numbers

50*30 = 1500

Answer 1

import java.util.ArrayList;

public class PeasantMultipication {

        /**
         * this method will multiply two values 
         * by using peasant multiply method
         * @param n1
         * @param n2
         * @return
         */
        public static int peasantMultiply(int n1,int n2)
        {
                //taken two array list for 
                //right hand side and left hand side
                ArrayList<Integer> leftSide=new ArrayList<Integer>();
                ArrayList<Integer> rightSide = new ArrayList<Integer>();
                
                //dividing the n1 by 2 until it greater than 1
                while(n1>1)
                {
                        //adding the values to leftside of array
                        leftSide.add(n1/2);
                        n1=n1/2;
                }
                /*doubling the number n2 (multiplying by 2 to result)
                 * till the size of leftSide array
                 */
                for(int i=0;i<leftSide.size();i++)
                {
                        rightSide.add(n2*2);
                        n2=n2*2;
                }
                //removing the even no from left side array and on same
                //index from right side array
                ArrayList<Integer> temp = new ArrayList<>();
                for(int i=0;i<leftSide.size();i++)
                {
                        //if divisible by 2 then removing
                        if(leftSide.get(i)%2==0)
                                continue;
                        temp.add(rightSide.get(i));
                }
                //reassigning the value to right side array
                rightSide=temp;
                int mulValue = 0;
                //looping through each variable and adding the values
                for(Integer i : rightSide)
                        mulValue += i;
                //returning the final value of multiplication
                return mulValue;
        }
        //main method for execitung the program
        public static void main(String[] args) {
                
                //multiplying value 1
                System.out.println("146 x 37 : "+peasantMultiply(146, 37)+" , Expected "+(146*37));
                System.out.println("212 x 54 : "+peasantMultiply(212, 54)+" , Expected "+(212*54));

        }

}