Commit 3c1efc3

@@ -5,7 +5,11 @@ import java.util.Scanner;
 
 public class ReversedSentence {
   public static String change5thPosition(String s) {
-    return "";
+    char[] result = new char[s.length()];
+
+    for (int i = 0; i < s.length(); i++) result[i] = (i > 0 && i % 5 == 0) ? 'z' : s.charAt(i);
+
+    return new String(result);
   }
 
   public static String printChar2DArray(char[][] arr) {

@@ -30,4 +30,9 @@ public class ReversedSentenceTest extends TestCase {
     assertEquals(
         "lamb little a had mary", ReversedSentence.reverseByWord("mary had a little lamb"));
   }
+
+  public void testChange5thPosition() {
+    assertEquals(
+        "mary zad azlittze lazb", ReversedSentence.change5thPosition("mary had a little lamb"));
+  }
 }