feat: Add ClearLeftmostSetBit new algorithm with Junit tests

Author: Hardvan

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

@@ -0,0 +1,25 @@
+package com.thealgorithms.bitmanipulation;
+
+public class ClearLeftmostSetBit {
+
+    /**
+     * Clears the leftmost set bit (1) of a given number.
+     * Step 1: Find the position of the leftmost set bit
+     * Step 2: Create a mask with all bits set except for the leftmost set bit
+     * Step 3: Clear the leftmost set bit using AND with the mask
+     *
+     * @param num The input number.
+     * @return The number after clearing the leftmost set bit.
+     */
+    public static int clearLeftmostSetBit(int num) {
+        int pos = 0;
+        int temp = num;
+        while (temp > 0) {
+            temp >>= 1;
+            pos++;
+        }
+
+        int mask = ~(1 << (pos - 1));
+        return num & mask;
+    }
+}

src/test/java/com/thealgorithms/bitmanipulation/ClearLeftmostSetBitTest.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 ClearLeftmostSetBitTest {
+
+    @Test
+    public void testClearLeftmostSetBit() {
+        assertEquals(10, ClearLeftmostSetBit.clearLeftmostSetBit(26)); // 11010 -> 01010
+        assertEquals(0, ClearLeftmostSetBit.clearLeftmostSetBit(1));   // 1 -> 0
+        assertEquals(3, ClearLeftmostSetBit.clearLeftmostSetBit(7));   // 111 -> 011
+        assertEquals(2, ClearLeftmostSetBit.clearLeftmostSetBit(6));  // 0110 -> 0010
+    }
+}