the wave

src/main/java/rocks/zipcode/io/quiz3/arrays/WaveGenerator.java

  */
 public class WaveGenerator {
     public static String[] wave(String str) {
-        return null;
+        String[] result = new String[countAlphas(str)];
+        String str2 = str.toLowerCase();
+        int idx = 0;
+        for (int i=0; i<str.length(); i++){
+            if (Character.isLetter(str.charAt(i))) {
+                result[idx] = str2.substring(0, i) + Character.toUpperCase(str2.charAt(i)) + str2.substring(i + 1);
+                idx++;
+            }
+        }
+        return result;
+    }
+
+    private static int countAlphas(String str){
+        int count = 0;
+        for (int i=0; i<str.length(); i++)
+            if (Character.isLetter(str.charAt(i)))
+                count++;
+        return count;
     }
 }