feat: Add BCDConverter new algorithm with Junit tests

Author: Hardvan

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

@@ -0,0 +1,47 @@
+package com.thealgorithms.conversions;
+
+/**
+ * Provides methods to convert between Decimal and Binary Coded Decimal (BCD).
+ * Decimal to BCD: Each decimal digit is converted to its 4-bit binary equivalent.
+ * Example: 123 -> 0001 0010 0011
+ *
+ * BCD to Decimal: Each 4-bit binary number is converted to its decimal equivalent.
+ * Example: 0001 0010 0011 -> 123
+ *
+ * Applications: Used in digital systems like calculators and clocks.
+ *
+ * @author Hardvan
+ */
+public final class BCDConverter {
+    private BCDConverter() {
+    }
+
+    /**
+     * Converts a decimal number to its BCD (Binary Coded Decimal) representation.
+     * @param number the decimal number to be converted.
+     * @return the BCD as a String.
+     */
+    public static String decimalToBCD(int number) {
+        StringBuilder bcd = new StringBuilder();
+        while (number > 0) {
+            int digit = number % 10;
+            bcd.insert(0, String.format("%04d", Integer.parseInt(Integer.toBinaryString(digit))));
+            number /= 10;
+        }
+        return bcd.toString();
+    }
+
+    /**
+     * Converts a BCD string back to its decimal representation.
+     * @param bcd the BCD string to convert.
+     * @return the decimal number as an integer.
+     */
+    public static int bcdToDecimal(String bcd) {
+        int decimal = 0;
+        for (int i = 0; i < bcd.length(); i += 4) {
+            String digitBinary = bcd.substring(i, i + 4);
+            decimal = decimal * 10 + Integer.parseInt(digitBinary, 2);
+        }
+        return decimal;
+    }
+}

src/test/java/com/thealgorithms/conversions/BCDConverterTest.java

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+package com.thealgorithms.conversions;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class BCDConverterTest {
+
+    @Test
+    public void testDecimalToBCD() {
+        assertEquals("00010010", BCDConverter.decimalToBCD(12));
+        assertEquals("001001000011", BCDConverter.decimalToBCD(243));
+    }
+
+    @Test
+    public void testBCDToDecimal() {
+        assertEquals(12, BCDConverter.bcdToDecimal("00010010"));
+        assertEquals(243, BCDConverter.bcdToDecimal("001001000011"));
+    }
+}