JMaths.java

/*
 * Copyright (C) 2016 Pi Developers
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @author Pi-Devs
 */



import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.security.Key;
import java.util.Scanner;

public class JMaths {

    private static final String ALGO = "AES";
    private static final byte[] keyValue =
            new byte[] { 'T', 'h', 'e', 'B', 'e', 's', 't',
                    'S', 'e', 'c', 'r','e', 't', 'K', 'e', 'y' };

    private static ScannerHelper sScannerHelper = new ScannerHelper(" : ");
    static int factorial(int n){
        if (n == 0)
            return 1;
        else
            return(n * factorial(n-1));
    }
    public static void main(String[] args) {
        String JMATHS = "       ____  ___      __  __        \n      / /  |/  /___ _/ /_/ /_  _____\n __  / / /|_/ / __ `/ __/ __ \\\\/ ___/\n/ /_/ / /  / / /_/ / /_/ / / (__  ) \n\\\\____/_/  /_/\\\\__,_/\\\\__/_/ /_/____/ ";
        System.out.println(JMATHS);
        System.out.println("              By Pi-Dev");
        System.out.println("=======================================");

        System.out.println("Would you like to do ?");
        int cursor = sScannerHelper.askAsInt(" 1) Generate Fibonacci Series :\n" +
                " 2)  Check Even or odd : \n" +
                " 3)  Check prime no : \n" +
                " 4)  Encrypt text : \n" +
                " 5)  Decrypt text : \n" +
                " 6)  Check Divisibility : \n" +
                " 7)  Compute Pascal Triangle : \n" +
                " 8)  Logarithms Calculator :\n"+
                " 9)  Compute Factorial : \n" +
                " 10) Solve a quadratic equation : \n"+
                " 11) Check Golden Ration Ration : \n"+
                " 99) For Exit ");
        if (cursor == 1) {
            fibonacci();
        }else if (cursor == 2) {
            checkEvenOdd();
        }else if (cursor == 3) {
            checkPrimeNo();
        }else if (cursor == 4) {
            encrypt();
        }else if (cursor == 5) {
            decrypt();
        }else if (cursor == 99) {

            System.exit(0);
        }else if (cursor == 7) {
            int row = sScannerHelper.askAsInt(" How many rows of pascal's triangle to generate ? ");
            genPasCal(row);
        }else if (cursor == 6) {
            int first_no = sScannerHelper.askAsInt(" Enter Desired Number Here");
            int second_no = sScannerHelper.askAsInt(" Enter number to be divided with");
            if (first_no %second_no != 0)
                System.out.println(("Your input is not divisible by " + second_no));
            else
                System.out.println("Your input is divisible by " + second_no);
        }else if (cursor == 8) {
            int type = sScannerHelper.askAsInt("Choose an option:\\n\\t1-Base n\\n\\t2-base 10\\n\\t3-natural logarithm");
            if (type == 1) {

                int nu = sScannerHelper.askAsInt(" Enter a number");
                int base = sScannerHelper.askAsInt(" Enter base");
                System.out.println(logOfBase(base,nu));
            }else if (type == 3) {

                long nu = sScannerHelper.askAsLong(" Enter a number");
                System.out.println(Math.log(nu));
            }else if (type == 2){
                long nu = sScannerHelper.askAsLong(" Enter a number");
                System.out.println(Math.log10(nu));
            }
        }else if (cursor == 9) {
            int nu = sScannerHelper.askAsInt(" Enter a number");
            System.out.println(factorial(nu));

        }else if (cursor==10) {

            System.out.println("Enter a,b,c co-efficient");
            int a = sScannerHelper.askAsInt(">");
            int b = sScannerHelper.askAsInt(">");
            int c = sScannerHelper.askAsInt(">");

            double temp1 = Math.sqrt(b * b - 4 * a * c);

            double root1 = (-b +  temp1) / (2*a) ;
            double root2 = (-b -  temp1) / (2*a) ;

            System.out.println("The roots of the Quadratic Equation are "+root1+" and "+root2);

        }else if (cursor== 11) {

          int n = sScannerHelper.askAsInt(" Enter first number");
            int m = sScannerHelper.askAsInt(" Enter second number");
            if (m > n ) {
                System.out.println("n must be greater than m");
            }else {
                float Q = ((float)n)/m;
                if ( Q > 1.68 && Q < 1.69) {
                    //print "\n Golden Ratio approximately exists between these 2 digits"
                    System.out.println(" Golden Ratio approximately exists between these 2 digits");
                }else {
                    System.out.println("  Golden Ratio  doesn't exist between these 2 digits");
                }
            }
        }else {


            System.out.println("Wrong Input");
        }
        Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
            @Override
            public void run() {
                System.gc();
            }
        }));


    }
    public static double logOfBase(int base, int num) {
        return Math.log(num) / Math.log(base);
    }
    private static void decrypt() {
        String text = sScannerHelper.askAsString("Enter your text to decrypt ");
        try {
            System.out.println(decrypt(text));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    private static void genPasCal(int rows) {

        for(int i =0;i<rows;i++) {
            int number = 1;
            System.out.format("%" + (rows - i) * 2 + "s", "");
            for (int j = 0; j <= i; j++) {
                System.out.format("%4d", number);
                number = number * (i - j) / (j + 1);

            }
            System.out.println();
        }

    }

    private static void encrypt() {
        String text = sScannerHelper.askAsString("Enter your text to encrypt ");
        try {
            System.out.println(encrypt(text));
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    public static String encrypt(String Data) throws Exception {
        Key key = generateKey();
        Cipher c = Cipher.getInstance(ALGO);
        c.init(Cipher.ENCRYPT_MODE, key);
        byte[] encVal = c.doFinal(Data.getBytes());
        return new BASE64Encoder().encode(encVal);
    }

    public static String decrypt(String encryptedData) throws Exception {
        Key key = generateKey();
        Cipher c = Cipher.getInstance(ALGO);
        c.init(Cipher.DECRYPT_MODE, key);
        byte[] decordedValue = new BASE64Decoder().decodeBuffer(encryptedData);
        byte[] decValue = c.doFinal(decordedValue);
        return new String(decValue);
    }
    private static Key generateKey() throws Exception {
        return new SecretKeySpec(keyValue, ALGO);
    }

    private static void checkPrimeNo() {
        int no = sScannerHelper.askAsInt("Enter your no");
        int i, m, flag = 0;
        m = no / 2;
        for (i = 2; i <= m; i++) {
            if (no % i == 0) {
                System.out.println("Number is not prime");
                flag = 1;
                break;
            }
        }
        if (flag == 0)
            System.out.println("Number is prime");

    }


    private static void checkEvenOdd() {
        int no = sScannerHelper.askAsInt("Enter your no");

        boolean even = no%2==0;
        if (even) {
            System.out.println(" No. '"+no+"' is even");
        }
        else {
            System.out.println(" No. '"+no+"' is odd");
        }
    }

    private static void fibonacci() {
        int no = sScannerHelper.askAsInt(" How many terms to generate");
        StringBuilder stringBuilder = new StringBuilder();
        String result = "";
        for (int i = 0 ; i < no ; i++) {

            stringBuilder.append(String.valueOf(fibonacci(i))).append(",");

        }
        if (stringBuilder.toString().endsWith(",")) {
            result = stringBuilder.toString().substring(0,stringBuilder.length()-1);
        }
        System.out.println("The no.s are " +result);
    }

    private static int fibonacci(int no) {
        if (no == 0 || no == 1) {
            return no;
        }else {
            return fibonacci(no - 1) + fibonacci(no - 2);
        }
    }
    private static class ScannerHelper {
        private Scanner mScanner;
        private String mSeparator;
        public ScannerHelper(String Separator) {
            this.mSeparator = Separator;
        }
        private void rebuildScanner() {
            mScanner = new Scanner(System.in);
        }
        public long askAsLong(String questions) {
            long result = 0;
            try {
                String q = askAsString(questions);
                result = Integer.parseInt(q);
            }catch (Exception e) {
                System.out.println("Your input is not Long . ");
                System.exit(0);
                askAsInt(questions);

            }
            return result;
        }

        public int askAsInt(String questions) {
            int result = 0;
            try {
                String q = askAsString(questions);
                result = Integer.parseInt(q);
            }catch (Exception e) {
                System.out.println("Your input is not Integer.");
                System.exit(0);
                askAsInt(questions);

            }
            return result;
        }
        public String askAsString(String questions) {
            System.out.println(questions + mSeparator + " ");
            rebuildScanner();
            String object = mScanner.next();
            mScanner = null;
            return object;
        }
    }

}