Add BONUS problems on recursion

BONUS/Recursion/ReverseString/README.md

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+# String Reversal
+
+WAP to reverse a string using recursion
+
+**Example** 
+
+```
+input: abcd
+output: dcba
+```
+
+## Solution 
+
+### [JavaScript Implementation](./reverseString.js)
+
+```js
+/**
+ * Reverse a string using recursion
+ * Implemented by - MadhavBahlMD
+ * @date 18/01/2019
+ */
+
+function reverseString (str) {
+    if (str.length === 1)  return str;
+    return reverseString(str.substring(1, str.length)) + str[0];
+}
+
+console.log (reverseString ('abcd'));
+```
+
+### [Java Implementation](./ReverseString.java)
+
+```java
+/**
+ * String Reversal using recursion
+ * @author MadhavBahlMD
+ * @date 18/01/2019
+ */
+
+import java.util.Scanner;
+
+public class ReverseString {
+    public static String reverse (String str) {
+        if (str.length() == 1)  return str;
+        return reverse (str.substring(1, str.length())) + str.charAt(0);
+    }
+
+    public static void main(String[] args) {
+        Scanner input = new Scanner(System.in);
+        System.out.println("/*/ ===== String Reversal using Recursion ==== */");
+
+        // Read the string
+        System.out.print("\nEnter the string to be reversed: ");
+        String str = input.nextLine();
+
+        // Print the result
+        System.out.println("Reversed string is: " + reverse(str));
+    }
+}
+```

BONUS/Recursion/ReverseString/ReverseString.java

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+/**
+ * String Reversal using recursion
+ * @author MadhavBahlMD
+ * @date 18/01/2019
+ */
+
+import java.util.Scanner;
+
+public class ReverseString {
+    public static String reverse (String str) {
+        if (str.length() == 1)  return str;
+        return reverse (str.substring(1, str.length())) + str.charAt(0);
+    }
+
+    public static void main(String[] args) {
+        Scanner input = new Scanner(System.in);
+        System.out.println("/*/ ===== String Reversal using Recursion ==== */");
+
+        // Read the string
+        System.out.print("\nEnter the string to be reversed: ");
+        String str = input.nextLine();
+
+        // Print the result
+        System.out.println("Reversed string is: " + reverse(str));
+    }
+}

BONUS/Recursion/ReverseString/reverseString.js

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+/**
+ * Reverse a string using recursion
+ * Implemented by - MadhavBahlMD
+ * @date 18/01/2019
+ */
+
+function reverseString (str) {
+    if (str.length === 1)  return str;
+    return reverseString(str.substring(1, str.length)) + str[0];
+}
+
+console.log (reverseString ('abcd'));