Exercise

package com.company;
import java.util.*;

public class Main {

    public static int fromBintoDec(char[] bin) {
        int number = 0;

        for (int i = 0; i < bin.length; i++) {
            if(bin[i] == '1'){
                number += Math.pow(2, bin.length - 1 - i);
            }
        }

        return number;
    }

    public static String fromCharToString(char[] arr){
        String output = "";

        for (char ch : arr) {
            output += ch;
        }

        return output;
    }


    public static int howManyZerosInBinary(char[] bin){
        int counter = 0;

        for (int i = 0; i < bin.length; i++) {
            if(bin[i] == '0'){
                counter++;
            }
        }

        return counter;
    }


    public static int sumOfOnesInBinary(char[] bin){
        int counter = 0;

        for (int i = 0; i < bin.length; i++) {
            if(bin[i] == '1'){
                counter++;
            }
        }

        return counter;
    }


    public static char[] fromDecToBinary(int number) {
        int elementsInBinary = 0;

        if(number < 0){
            number *= -1;
        }

        char[] binary;

        while(number > Math.pow(2, elementsInBinary)){
            elementsInBinary++;
        }
        binary = new char[elementsInBinary];


        for (int i = 0; i < binary.length; i++) {
            int powerOfTwo = (int)Math.pow(2, binary.length - 1 - i);

            if(number - powerOfTwo >= 0){
                binary[i] = '1';
                number -= powerOfTwo;
            }
            else{
                binary[i] = '0';
            }
        }

        return binary;
    }



    public static char[] straightCodeOfDecimalNumber(int number){
        boolean numberIsNegative = number < 0;
        char[] numberAsBinary = fromDecToBinary(number);
        char[] straightCode = new char[numberAsBinary.length + 1];

        if(numberIsNegative)
        {
            straightCode[0] = '1';
        }else{
            straightCode[0] = '0';
        }

        for (int i = 1; i < straightCode.length; i++) {
            straightCode[i] = numberAsBinary[i - 1];
        }

        return straightCode;
    }


    public static char[] reversedCodeFromDecimalNumber(int number){
        boolean numberIsNegative = number < 0;
        char[] numberAsBinary = fromDecToBinary(number);
        char[] reversedCode = new char[numberAsBinary.length + 1];

        if(numberIsNegative)
        {
            reversedCode[0] = '1';

            for (int i = 1; i < reversedCode.length; i++) {
                if(numberAsBinary[i - 1] == '1') {
                    reversedCode[i] = '0';
                }else{
                    reversedCode[i] = '1';
                }
            }

        }else{
            reversedCode[0] = '0';

            for (int i = 1; i < reversedCode.length; i++) {
                reversedCode[i] = numberAsBinary[i - 1];
            }
        }



        return reversedCode;
    }


    public static String sumOfBinaryNumber(String n1, String n2) {
        int length = Math.max(n1.length(), n2.length());
        String sum;

        int temp = Integer.parseInt(n1, 2) + Integer.parseInt(n2, 2);

        sum = Integer.toBinaryString(temp);

        System.out.println(sum);

        return sum;
    }


    public static char[] additionalCodeFromDecimalNumber(int number){
        boolean numberIsNegative = number < 0;
        char[] numberAsBinary = fromDecToBinary(number);
        ArrayList<Character> additionalCode = new ArrayList<>();

        if(numberIsNegative) {
            for (int i = 0; i < numberAsBinary.length; i++) {
                if(numberAsBinary[i] == '1') {
                    numberAsBinary[i] = '0';
                }else{
                    numberAsBinary[i] = '1';
                }
            }

            char[] temp = sumOfBinaryNumber(fromCharToString(numberAsBinary), "1").toCharArray();

            additionalCode.add('1');
            for (char ch : temp) {
                additionalCode.add(ch);
            }

        }else{
            additionalCode.add('0');

            for (char ch : numberAsBinary) {
                additionalCode.add(ch);
            }
        }

        char[] output = new char[additionalCode.size()];

        for (int i = 0; i < output.length; i++) {
            output[i] = additionalCode.get(i);
        }

        return output;
    }


    public static int subtractWithoutOperator(int a, int b){
        int c = 0;
        int result = 0;
        boolean swap = false;

        if(a < b){
            int temp = a;
            a = b;
            b = temp;
            swap = true;
        }

        c = a ^ b;
        c = c & b;
        c = c << 1;
        a = a ^ b;
        result = a ^ c;

        if(swap){
            result *= -1;
        }


        return result;
    }
}