From d7231e88a06470ee865332eb2db77b7344a0d768 Mon Sep 17 00:00:00 2001
From: Tanmay Singh <tanmay30iit@gmail.com>
Date: Sun, 13 Oct 2024 02:28:51 +0530
Subject: [PATCH] feat: Add BcdConversion algo with JUnit tests

---
 DIRECTORY.md                                  |  2 +
 .../bitmanipulation/BcdConversion.java        | 58 +++++++++++++++++
 .../bitmanipulation/BcdConversionTest.java    | 65 +++++++++++++++++++
 3 files changed, 125 insertions(+)
 create mode 100644 src/main/java/com/thealgorithms/bitmanipulation/BcdConversion.java
 create mode 100644 src/test/java/com/thealgorithms/bitmanipulation/BcdConversionTest.java

diff --git a/DIRECTORY.md b/DIRECTORY.md
index 30fa2cbee199..af956a1a26ed 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -23,6 +23,7 @@
             * [WordPatternMatcher](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/backtracking/WordPatternMatcher.java)
             * [WordSearch](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/backtracking/WordSearch.java)
           * bitmanipulation
+            * [BcdConversion](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/BcdConversion.java)
             * [BinaryPalindromeCheck](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/BinaryPalindromeCheck.java)
             * [BitSwap](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/BitSwap.java)
             * [ClearLeftmostSetBit](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/ClearLeftmostSetBit.java)
@@ -654,6 +655,7 @@
             * [WordPatternMatcherTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/backtracking/WordPatternMatcherTest.java)
             * [WordSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/backtracking/WordSearchTest.java)
           * bitmanipulation
+            * [BcdConversionTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/BcdConversionTest.java)
             * [BinaryPalindromeCheckTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/BinaryPalindromeCheckTest.java)
             * [BitSwapTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/BitSwapTest.java)
             * [ClearLeftmostSetBitTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/ClearLeftmostSetBitTest.java)
diff --git a/src/main/java/com/thealgorithms/bitmanipulation/BcdConversion.java b/src/main/java/com/thealgorithms/bitmanipulation/BcdConversion.java
new file mode 100644
index 000000000000..3cf8411816c7
--- /dev/null
+++ b/src/main/java/com/thealgorithms/bitmanipulation/BcdConversion.java
@@ -0,0 +1,58 @@
+package com.thealgorithms.bitmanipulation;
+
+/**
+ * This class provides methods to convert between BCD (Binary-Coded Decimal) and binary.
+ *
+ * Binary-Coded Decimal (BCD) is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of binary digits, usually four or eight.
+ *
+ * For more information, refer to the
+ * <a href="https://en.wikipedia.org/wiki/Binary-coded_decimal">Binary-Coded Decimal</a> Wikipedia page.
+ *
+ * <b>Example usage:</b>
+ * <pre>
+ * int binary = BcdConversion.bcdToBinary(0x1234);
+ * System.out.println("BCD 0x1234 to binary: " + binary); // Output: 1234
+ *
+ * int bcd = BcdConversion.binaryToBcd(1234);
+ * System.out.println("Binary 1234 to BCD: " + Integer.toHexString(bcd)); // Output: 0x1234
+ * </pre>
+ */
+public final class BcdConversion {
+    private BcdConversion() {
+    }
+    /**
+     * Converts a BCD (Binary-Coded Decimal) number to binary.
+     *
+     * @param bcd The BCD number.
+     * @return The corresponding binary number.
+     */
+    public static int bcdToBinary(int bcd) {
+        int binary = 0;
+        int multiplier = 1;
+        while (bcd > 0) {
+            int digit = bcd & 0xF; // Extract the last 4 bits (one BCD digit)
+            binary += digit * multiplier;
+            multiplier *= 10;
+            bcd >>= 4; // Shift right by 4 bits to process the next BCD digit
+        }
+        return binary;
+    }
+
+    /**
+     * Converts a binary number to BCD (Binary-Coded Decimal).
+     *
+     * @param binary The binary number.
+     * @return The corresponding BCD number.
+     */
+    public static int binaryToBcd(int binary) {
+        int bcd = 0;
+        int shift = 0;
+        while (binary > 0) {
+            int digit = binary % 10; // Extract the last decimal digit
+            bcd |= (digit << (shift * 4)); // Shift the digit to the correct BCD position
+            binary /= 10; // Remove the last decimal digit
+            shift++;
+        }
+        return bcd;
+    }
+}
diff --git a/src/test/java/com/thealgorithms/bitmanipulation/BcdConversionTest.java b/src/test/java/com/thealgorithms/bitmanipulation/BcdConversionTest.java
new file mode 100644
index 000000000000..85221d92ad42
--- /dev/null
+++ b/src/test/java/com/thealgorithms/bitmanipulation/BcdConversionTest.java
@@ -0,0 +1,65 @@
+package com.thealgorithms.bitmanipulation;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for the BcdConversion class.
+ */
+public class BcdConversionTest {
+
+    /**
+     * Test the bcdToBinary method with a BCD number.
+     */
+    @Test
+    public void testBcdToBinary() {
+        int binary = BcdConversion.bcdToBinary(0x1234);
+        assertEquals(1234, binary); // BCD 0x1234 should convert to binary 1234
+    }
+
+    /**
+     * Test the binaryToBcd method with a binary number.
+     */
+    @Test
+    public void testBinaryToBcd() {
+        int bcd = BcdConversion.binaryToBcd(1234);
+        assertEquals(0x1234, bcd); // Binary 1234 should convert to BCD 0x1234
+    }
+
+    /**
+     * Test the bcdToBinary method with zero.
+     */
+    @Test
+    public void testBcdToBinaryZero() {
+        int binary = BcdConversion.bcdToBinary(0x0);
+        assertEquals(0, binary); // BCD 0x0 should convert to binary 0
+    }
+
+    /**
+     * Test the binaryToBcd method with zero.
+     */
+    @Test
+    public void testBinaryToBcdZero() {
+        int bcd = BcdConversion.binaryToBcd(0);
+        assertEquals(0x0, bcd); // Binary 0 should convert to BCD 0x0
+    }
+
+    /**
+     * Test the bcdToBinary method with a single digit BCD number.
+     */
+    @Test
+    public void testBcdToBinarySingleDigit() {
+        int binary = BcdConversion.bcdToBinary(0x7);
+        assertEquals(7, binary); // BCD 0x7 should convert to binary 7
+    }
+
+    /**
+     * Test the binaryToBcd method with a single digit binary number.
+     */
+    @Test
+    public void testBinaryToBcdSingleDigit() {
+        int bcd = BcdConversion.binaryToBcd(7);
+        assertEquals(0x7, bcd); // Binary 7 should convert to BCD 0x7
+    }
+}