Added Removing stars and complex number multiplication program

src/main/java/com/thealgorithms/strings/ComplexNumber.java

@@ -0,0 +1,44 @@
+import java.util.Scanner;
+
+public class ComplexMultiply {
+     /**
+     * Multiplies two complex numbers given as strings in "a+bi" format.
+     * Parses the strings, performs multiplication, and returns the product.
+     * 
+     * num1 First complex number string
+     * num2 Second complex number string
+     * return the product as a string in "x+yi" format
+     */
+    public static String multiply(String num1, String num2) {
+        int n1 = num1.indexOf('+');
+        int a = Integer.parseInt(num1.substring(0, n1));
+        int b = Integer.parseInt(num1.substring(n1 + 1, num1.length() - 1)); // exclude 'i'
+
+        int n2 = num2.indexOf('+');
+        int c = Integer.parseInt(num2.substring(0, n2));
+        int d = Integer.parseInt(num2.substring(n2 + 1, num2.length() - 1)); // exclude 'i'
+
+        int real = a * c - b * d; // real part of product
+        int imag = a * d + b * c; // imaginary part of product
+
+        return real + "+" + imag + "i";
+    }
+
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+
+        // Prompt user to enter first complex number
+        System.out.print("num1: ");
+        String num1 = scanner.nextLine();
+
+        // Prompt user to enter second complex number
+        System.out.print("num2: ");
+        String num2 = scanner.nextLine();
+
+        // Perform multiplication and display result
+        String result = multiply(num1, num2);
+        System.out.println("Output: " + result);
+
+        scanner.close();
+    }
+}

src/main/java/com/thealgorithms/strings/Removing stars.java

@@ -0,0 +1,58 @@
+import java.util.Scanner;
+
+public class RemoveStars {
+
+    /**
+     * Removes stars from the input string by deleting the closest non-star character to the left of each star along with the star itself.
+     * 
+     * The input string containing stars (*)
+     * The resulting string after all stars and their closest left characters are removed
+     */
+    public static String removeStars(String s1) {
+        // Use StringBuilder for efficient string manipulation
+        StringBuilder sc = new StringBuilder();
+
+        // Loop through each character in the input string
+        for (int i = 0; i < s1.length(); i++) {
+            char ch = s1.charAt(i);
+
+            if (ch == '*') {
+                // When star is found, remove last character from sc if it exists
+                if (sc.length() > 0) {
+                    sc.deleteCharAt(sc.length() - 1);
+                }
+            } else {
+                // Append non-star characters to sc
+                sc.append(ch);
+            }
+        }
+
+        // Convert StringBuilder to string and return
+        return sc.toString();
+    }
+
+    public static void main(String[] args) {
+        // Create a Scanner object to read user input from the console
+        Scanner scanner = new Scanner(System.in);
+
+        // Prompt the user to enter a string containing stars
+        System.out.print("Input: ");
+
+        // Read the entire line entered by the user
+        if (scanner.hasNextLine()) {
+            String input = scanner.nextLine();
+
+            // Call the removeStars method to process the string input
+            String output = removeStars(input);
+
+            // Print the resulting string after removing stars and their left characters
+            System.out.println("Output: " + output);
+        } else {
+            // Inform user if no input was provided
+            System.out.println("No input provided.");
+        }
+
+        // Close the scanner to free resources
+        scanner.close();
+    }
+}