Merge branch 'TheAlgorithms:master' into master

Author: Vatsalya-24

src/main/java/com/thealgorithms/conversions/BinaryToOctal.java

@@ -1,50 +1,45 @@
 package com.thealgorithms.conversions;
 
-import java.util.Scanner;
-
-/**
- * Converts any Binary number to an Octal Number
- *
- * @author Zachary Jones
- */
 public final class BinaryToOctal {
-    private BinaryToOctal() {
-    }
+    private static final int BITS_PER_OCTAL_DIGIT = 3;
+    private static final int BINARY_BASE = 2;
+    private static final int DECIMAL_BASE = 10;
 
-    /**
-     * Main method
-     *
-     * @param args Command line arguments
-     */
-    public static void main(String[] args) {
-        Scanner sc = new Scanner(System.in);
-        System.out.println("Input the binary number: ");
-        int b = sc.nextInt();
-        System.out.println("Octal equivalent: " + convertBinaryToOctal(b));
-        sc.close();
+    private BinaryToOctal() {
     }
 
     /**
      * This method converts a binary number to an octal number.
      *
      * @param binary The binary number
      * @return The octal number
+     * @throws IllegalArgumentException if the input is not a valid binary number
      */
     public static String convertBinaryToOctal(int binary) {
-        String octal = "";
-        int currBit = 0;
-        int j = 1;
+        if (binary == 0) {
+            return "0";
+        }
+
+        if (!String.valueOf(binary).matches("[01]+")) {
+            throw new IllegalArgumentException("Input is not a valid binary number.");
+        }
+
+        StringBuilder octal = new StringBuilder();
+        int currentBit;
+        int bitValueMultiplier = 1;
+
         while (binary != 0) {
-            int code3 = 0;
-            for (int i = 0; i < 3; i++) {
-                currBit = binary % 10;
-                binary = binary / 10;
-                code3 += currBit * j;
-                j *= 2;
+            int octalDigit = 0;
+            for (int i = 0; i < BITS_PER_OCTAL_DIGIT && binary != 0; i++) {
+                currentBit = binary % DECIMAL_BASE;
+                binary /= DECIMAL_BASE;
+                octalDigit += currentBit * bitValueMultiplier;
+                bitValueMultiplier *= BINARY_BASE;
             }
-            octal = code3 + octal;
-            j = 1;
+            octal.insert(0, octalDigit);
+            bitValueMultiplier = 1; // Reset multiplier for the next group
         }
-        return octal;
+
+        return octal.toString();
     }
 }

src/main/java/com/thealgorithms/conversions/DecimalToBinary.java

@@ -1,63 +1,49 @@
 package com.thealgorithms.conversions;
 
-import java.util.Scanner;
-
 /**
- * This class converts a Decimal number to a Binary number
+ * This class provides methods to convert a decimal number to a binary number.
  */
 final class DecimalToBinary {
+    private static final int BINARY_BASE = 2;
+    private static final int DECIMAL_MULTIPLIER = 10;
+
     private DecimalToBinary() {
     }
 
     /**
-     * Main Method
-     *
-     * @param args Command Line Arguments
+     * Converts a decimal number to a binary number using a conventional algorithm.
+     * @param decimalNumber the decimal number to convert
+     * @return the binary representation of the decimal number
      */
-    public static void main(String[] args) {
-        conventionalConversion();
-        bitwiseConversion();
-    }
+    public static int convertUsingConventionalAlgorithm(int decimalNumber) {
+        int binaryNumber = 0;
+        int position = 1;
 
-    /**
-     * This method converts a decimal number to a binary number using a
-     * conventional algorithm.
-     */
-    public static void conventionalConversion() {
-        int n;
-        int b = 0;
-        int c = 0;
-        int d;
-        Scanner input = new Scanner(System.in);
-        System.out.printf("Conventional conversion.%n Enter the decimal number: ");
-        n = input.nextInt();
-        while (n != 0) {
-            d = n % 2;
-            b = b + d * (int) Math.pow(10, c++);
-            n /= 2;
-        } // converting decimal to binary
-        System.out.println("\tBinary number: " + b);
-        input.close();
+        while (decimalNumber > 0) {
+            int remainder = decimalNumber % BINARY_BASE;
+            binaryNumber += remainder * position;
+            position *= DECIMAL_MULTIPLIER;
+            decimalNumber /= BINARY_BASE;
+        }
+
+        return binaryNumber;
     }
 
     /**
-     * This method converts a decimal number to a binary number using a bitwise
-     * algorithm
+     * Converts a decimal number to a binary number using a bitwise algorithm.
+     * @param decimalNumber the decimal number to convert
+     * @return the binary representation of the decimal number
      */
-    public static void bitwiseConversion() {
-        int n;
-        int b = 0;
-        int c = 0;
-        int d;
-        Scanner input = new Scanner(System.in);
-        System.out.printf("Bitwise conversion.%n Enter the decimal number: ");
-        n = input.nextInt();
-        while (n != 0) {
-            d = (n & 1);
-            b += d * (int) Math.pow(10, c++);
-            n >>= 1;
+    public static int convertUsingBitwiseAlgorithm(int decimalNumber) {
+        int binaryNumber = 0;
+        int position = 1;
+
+        while (decimalNumber > 0) {
+            int leastSignificantBit = decimalNumber & 1;
+            binaryNumber += leastSignificantBit * position;
+            position *= DECIMAL_MULTIPLIER;
+            decimalNumber >>= 1;
         }
-        System.out.println("\tBinary number: " + b);
-        input.close();
+        return binaryNumber;
     }
 }

src/main/java/com/thealgorithms/conversions/DecimalToHexaDecimal.java

@@ -0,0 +1,42 @@
+package com.thealgorithms.conversions;
+
+/**
+ * This class provides a method to convert a decimal number to a hexadecimal string.
+ */
+final class DecimalToHexadecimal {
+    private static final int SIZE_OF_INT_IN_HALF_BYTES = 8;
+    private static final int NUMBER_OF_BITS_IN_HALF_BYTE = 4;
+    private static final int HALF_BYTE_MASK = 0x0F;
+    private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
+
+    private DecimalToHexadecimal() {
+    }
+
+    /**
+     * Converts a decimal number to a hexadecimal string.
+     * @param decimal the decimal number to convert
+     * @return the hexadecimal representation of the decimal number
+     */
+    public static String decToHex(int decimal) {
+        StringBuilder hexBuilder = new StringBuilder(SIZE_OF_INT_IN_HALF_BYTES);
+        for (int i = SIZE_OF_INT_IN_HALF_BYTES - 1; i >= 0; --i) {
+            int currentHalfByte = decimal & HALF_BYTE_MASK;
+            hexBuilder.insert(0, HEX_DIGITS[currentHalfByte]);
+            decimal >>= NUMBER_OF_BITS_IN_HALF_BYTE;
+        }
+        return removeLeadingZeros(hexBuilder.toString().toLowerCase());
+    }
+
+    private static String removeLeadingZeros(String str) {
+        if (str == null || str.isEmpty()) {
+            return str;
+        }
+
+        int i = 0;
+        while (i < str.length() && str.charAt(i) == '0') {
+            i++;
+        }
+
+        return i == str.length() ? "0" : str.substring(i);
+    }
+}