Added Removing stars and Complex NumberMultiplication

Author: Ganesh-PC018

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

@@ -0,0 +1,37 @@
+package main.java.com.thealgorithms.strings;
+
+
+public class ComplexNumberMultiplication {
+    private ComplexNumberMultiplication() {
+        // Prevent instantiation
+    }
+    /**
+     * Multiplies two complex numbers given as strings.
+     *
+     * @param num1 the first complex number in "a+bi" format
+     * @param num2 the second complex number in "c+di" format
+     * @return the product of the two complex numbers, also in "x+yi" format
+     */
+    public static String multiply(String num1, String num2) {
+        int[] complex1 = parseComplex(num1);
+        int[] complex2 = parseComplex(num2);
+
+        int realPart = complex1[0] * complex2[0] - complex1[1] * complex2[1];
+        int imaginaryPart = complex1[0] * complex2[1] + complex1[1] * complex2[0];
+
+        return realPart + "+" + imaginaryPart + "i";
+    }
+
+    /**
+     * Parses a complex number string into its integer components.
+     *
+     * @param complexStr complex number string in "a+bi" format
+     * @return an array where index 0 is the real part, and index 1 is the imaginary part
+     */
+    private static int[] parseComplex(String complexStr) {
+        String[] parts = complexStr.split("\\+");
+        int real = Integer.parseInt(parts[0]);
+        int imaginary = Integer.parseInt(parts[1].replace("i", ""));
+        return new int[]{real, imaginary};
+    }
+}

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

@@ -0,0 +1,45 @@
+package main.java.com.thealgorithms.strings;
+import java.util.*;
+/**
+ * A utility class to remove stars ('*') from a given string.
+ * Each '*' deletes the character immediately before it.
+ *
+ * <p>Example:
+ * <pre>
+ * Input:  "leet**cod*e"
+ * Output: "lecoe"
+ * </pre>
+ *
+ * <p>This implementation uses a stack-like approach for efficient character removal.
+ * @author Ganesh Mane
+ */
+public final class RemovingStars{
+    private RemovingStars(){
+        //prevent instantiation
+    }
+
+     /**
+     * Removes stars from the given string, simulating backspace behavior.
+     *
+     * @param text the input string possibly containing '*'
+     * @return the final string after removing stars and their preceding characters
+     */
+    public static void main(String[] args) {
+        String s = "leet**cod*e";
+        System.out.println(removeStarsFromString(s));
+    }
+    public static String removeStarsFromString(String s){
+        StringBuilder sb = new StringBuilder();
+        for(char ch : s.toCharArray()){
+            if(ch == '*'){
+                if (sb.length() > 0) {
+                    sb.deleteCharAt(sb.length() - 1);
+                }
+            }else{
+                sb.append(ch);
+            }
+        }
+
+        return sb.toString();
+    }
+}