feat: Add countLeadingZeros new algorithm with Junit tests (#5703)

Author: Hardvan

DIRECTORY.md

@@ -25,6 +25,7 @@
           * bitmanipulation
             * [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)
+            * [CountLeadingZeros](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/CountLeadingZeros.java)
             * [CountSetBits](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/CountSetBits.java)
             * [HighestSetBit](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/HighestSetBit.java)
             * [IndexOfRightMostSetBit](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/IndexOfRightMostSetBit.java)
@@ -649,6 +650,7 @@
           * bitmanipulation
             * [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)
+            * [CountLeadingZerosTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/CountLeadingZerosTest.java)
             * [CountSetBitsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/CountSetBitsTest.java)
             * [HighestSetBitTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/HighestSetBitTest.java)
             * [IndexOfRightMostSetBitTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/IndexOfRightMostSetBitTest.java)

src/main/java/com/thealgorithms/bitmanipulation/CountLeadingZeros.java

@@ -0,0 +1,39 @@
+package com.thealgorithms.bitmanipulation;
+
+/**
+ * CountLeadingZeros class contains a method to count the number of leading zeros in the binary representation of a number.
+ * The number of leading zeros is the number of zeros before the leftmost 1 bit.
+ * For example, the number 5 has 29 leading zeros in its 32-bit binary representation.
+ * The number 0 has 32 leading zeros.
+ * The number 1 has 31 leading zeros.
+ * The number -1 has no leading zeros.
+ *
+ * @author Hardvan
+ */
+public final class CountLeadingZeros {
+    private CountLeadingZeros() {
+    }
+
+    /**
+     * Counts the number of leading zeros in the binary representation of a number.
+     * Method: Keep shifting the mask to the right until the leftmost bit is 1.
+     * The number of shifts is the number of leading zeros.
+     *
+     * @param num The input number.
+     * @return The number of leading zeros.
+     */
+    public static int countLeadingZeros(int num) {
+        if (num == 0) {
+            return 32;
+        }
+
+        int count = 0;
+        int mask = 1 << 31;
+        while ((mask & num) == 0) {
+            count++;
+            mask >>>= 1;
+        }
+
+        return count;
+    }
+}

src/test/java/com/thealgorithms/bitmanipulation/CountLeadingZerosTest.java

@@ -0,0 +1,16 @@
+package com.thealgorithms.bitmanipulation;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class CountLeadingZerosTest {
+
+    @Test
+    public void testCountLeadingZeros() {
+        assertEquals(29, CountLeadingZeros.countLeadingZeros(5)); // 000...0101 has 29 leading zeros
+        assertEquals(32, CountLeadingZeros.countLeadingZeros(0)); // 000...0000 has 32 leading zeros
+        assertEquals(31, CountLeadingZeros.countLeadingZeros(1)); // 000...0001 has 31 leading zeros
+        assertEquals(0, CountLeadingZeros.countLeadingZeros(-1)); // No leading zeros in negative number (-1)
+    }
+}