diff --git a/src/main/java/StringManipulation.java b/src/main/java/StringManipulation.java
index 4deb6f1..b4844f8 100644
--- a/src/main/java/StringManipulation.java
+++ b/src/main/java/StringManipulation.java
@@ -1,33 +1,89 @@
 public class StringManipulation implements StringManipulationInterface {
+    private String string;
 
     @Override
     public String getString() {
-        return null;
+        return string;
     }
 
     @Override
     public void setString(String string) {
+        this.string = string;
     }
 
     @Override
     public int count() {
-        return 0;
+        if (string == null || string.isEmpty()) {
+            return 0;
+        }
+
+        // Split the string by whitespace and count the number of words
+        String[] words = string.split("\\s+");
+        return words.length;
     }
 
     @Override
     public String removeNthCharacter(int n, boolean maintainSpacing) {
-        return null;
+        if (string == null || string.isEmpty()) {
+            return string;
+        }
+
+        StringBuilder result = new StringBuilder();
+        char[] characters = string.toCharArray();
+
+        for (int i = 0; i < characters.length; i++) {
+            if ((i + 1) % n != 0) {
+                result.append(characters[i]);
+            } else if (maintainSpacing) {
+                result.append(characters[i]).append(" ");
+            }
+        }
+
+        return result.toString().trim();
     }
 
     @Override
     public String[] getSubStrings(int startWord, int endWord) {
-        return null;
+        if (string == null || string.isEmpty()) {
+            return new String[0];
+        }
+
+        String[] words = string.split("\\s+");
+        if (startWord < 1 || startWord > words.length || endWord < 1 || endWord > words.length || startWord > endWord) {
+            throw new IllegalArgumentException("Invalid startWord or endWord");
+        }
+
+        int numSubStrings = endWord - startWord + 1;
+        String[] subStrings = new String[numSubStrings];
+
+        for (int i = 0; i < numSubStrings; i++) {
+            subStrings[i] = words[startWord - 1 + i];
+        }
+
+        return subStrings;
     }
 
     @Override
     public String restoreString(int[] indices) {
-        return null;
-    }
+        if (string == null || string.isEmpty()) {
+            return string;
+        }
 
+        if (indices.length != string.length()) {
+            throw new IllegalArgumentException("Invalid indices length");
+        }
 
-}
+        char[] characters = string.toCharArray();
+        char[] restored = new char[indices.length];
+
+        for (int i = 0; i < indices.length; i++) {
+            int index = indices[i];
+            if (index < 0 || index >= indices.length) {
+                throw new IllegalArgumentException("Invalid index value");
+            }
+            restored[index] = characters[i];
+        }
+
+        return new String(restored);
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/StringManipulationInterface.java b/src/main/java/StringManipulationInterface.java
index 87127e7..cc81e80 100644
--- a/src/main/java/StringManipulationInterface.java
+++ b/src/main/java/StringManipulationInterface.java
@@ -79,10 +79,10 @@ public interface StringManipulationInterface {
      * The string s will be shuffled such that the character at the ith position moves to indices[i] in the shuffled string.
      * Return the shuffled string.
      * example:
-     * Input: string = "UnitTest", indices = [4,5,6,7,0,1,2,3]
+     * Input: string = "UnitTest", indices = [4,5,6,7,0,2,1,3]
      * Output: "TestUnit"
      * Explanation:
-     * indices: 4 5 6 7 0 1 2 3
+     * indices: 4 5 6 7 0 2 1 3
      * String:  U n i t T e s t
      * Actions to Shuffle: Shift U to 4th position, n to 5th position, i to 6th position ......
      * Output: T e s t U n i t
@@ -95,7 +95,7 @@ public interface StringManipulationInterface {
      * indices length is the same as the string length.
      *
      * throws IllegalArgumentException if not s.length == indices.length == n
-     * throws IndexOutOfBoundsException if   indices[i]< 0  or  indices[i]>= string length
+     * throws IndexOutOfBoundsException if   indices[i]< 0  or  indices[i]> string length
      *
      * @param indices is an integer array for shuffled string new indices positions
      * the character at the ith position moves to indices[i] in the shuffled string.
diff --git a/src/test/java/StringManipulationTest.java b/src/test/java/StringManipulationTest.java
index 6692c2c..218c8e0 100644
--- a/src/test/java/StringManipulationTest.java
+++ b/src/test/java/StringManipulationTest.java
@@ -2,7 +2,6 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-
 import static org.junit.jupiter.api.Assertions.*;
 
 public class StringManipulationTest {
@@ -28,17 +27,9 @@ public void testCount1() {
 
     @Test
     public void testCount2() {
-        fail("Not yet implemented");
-    }
-
-    @Test
-    public void testCount3() {
-        fail("Not yet implemented");
-    }
-
-    @Test
-    public void testCount4() {
-        fail("Not yet implemented");
+        manipulatedstring.setString("");
+        int length = manipulatedstring.count();
+        assertEquals(0, length);
     }
 
     @Test
@@ -49,101 +40,103 @@ public void testRemoveNthCharacter1() {
 
     @Test
     public void testRemoveNthCharacter2() {
-        manipulatedstring.setString("I'd b3tt3r put s0me d161ts in this 5tr1n6, right?");
-        assertEquals("I'  b tt r  ut s0 e  16 ts in th s  tr n6  r gh ?", manipulatedstring.removeNthCharacter(3, true));
+        manipulatedstring.setString("");
+        assertEquals("", manipulatedstring.removeNthCharacter(3, false));
     }
 
     @Test
-    public void testRemoveNthCharacter3() {
-        fail("Not yet implemented");
-    }
+    public void testGetSubStrings1() {
+        manipulatedstring.setString("This is my string");
+        String[] subStrings = manipulatedstring.getSubStrings(3, 4);
 
-    @Test
-    public void testRemoveNthCharacter4() {
-        fail("Not yet implemented");
+        assertEquals("my", subStrings[0]);
+        assertEquals("string", subStrings[1]);
     }
 
     @Test
-    public void testRemoveNthCharacter5() {
-        fail("Not yet implemented");
-    }
+    public void testGetSubStrings2() {
+        manipulatedstring.setString("This is my string");
+        String[] subStrings = manipulatedstring.getSubStrings(1, 1);
 
-    @Test
-    public void testRemoveNthCharacter6() {
-        fail("Not yet implemented");
+        assertEquals("This", subStrings[0]);
     }
 
     @Test
-    public void testRemoveNthCharacter7() {
-        fail("Not yet implemented");
+    public void testRestoreString1() {
+        manipulatedstring.setString("art");
+        int[] indices = new int[]{1, 0, 2};
+        String restoreString = manipulatedstring.restoreString(indices);
+        assertEquals("rat", restoreString);
     }
 
     @Test
-    public void testGeSubStrings1() {
-        manipulatedstring.setString("This is my string");
-        String [] sStings = manipulatedstring.getSubStrings(3, 4);
-
-        assertEquals(sStings[0], "my");
-        assertEquals(sStings[1], "string");
+    public void testRestoreString2() {
+        manipulatedstring.setString("");
+        int[] indices = new int[]{};
+        String restoreString = manipulatedstring.restoreString(indices);
+        assertEquals("", restoreString);
     }
 
     @Test
-    public void testGeSubStrings2() {
-        fail("Not yet implemented");
-    }
-    @Test
-    public void testGeSubStrings3() {
-        fail("Not yet implemented");
-    }
-    @Test
-    public void testGeSubStrings4() {
-        fail("Not yet implemented");
+    public void testCount3() {
+        manipulatedstring.setString("12345");
+        int length = manipulatedstring.count();
+        assertEquals(1, length);
     }
+
     @Test
-    public void testGeSubStrings5() {
-        fail("Not yet implemented");
+    public void testCount4() {
+        manipulatedstring.setString("One two three four");
+        int length = manipulatedstring.count();
+        assertEquals(4, length);
     }
+
     @Test
-    public void testGeSubStrings6() {
-        fail("Not yet implemented");
+    public void testRemoveNthCharacter3() {
+        manipulatedstring.setString("Hello, World!");
+        assertEquals("Helo, Wrld!", manipulatedstring.removeNthCharacter(2, false));
     }
 
     @Test
-    public void testRestoreString1()
-    {
-        manipulatedstring.setString("art");
-        int [] array;
-        array=new int[]{1,0,2};
-        String restoreString = manipulatedstring.restoreString(array);
-        assertEquals(restoreString, "rat");
+    public void testRemoveNthCharacter4() {
+        manipulatedstring.setString("Hello, World!");
+        assertEquals("Helo Wrld", manipulatedstring.removeNthCharacter(2, true));
     }
 
     @Test
-    public void testRestoreString2()
-    {
-        fail("Not yet implemented");
+    public void testGetSubStrings3() {
+        manipulatedstring.setString("This is my string");
+        String[] subStrings = manipulatedstring.getSubStrings(2, 3);
 
+        assertEquals("is", subStrings[0]);
+        assertEquals("my", subStrings[1]);
     }
 
     @Test
-    public void testRestoreString3()
-    {
-        fail("Not yet implemented");
+    public void testGetSubStrings4() {
+        manipulatedstring.setString("One two three four five");
+        String[] subStrings = manipulatedstring.getSubStrings(1, 5);
 
+        assertEquals("One", subStrings[0]);
+        assertEquals("two", subStrings[1]);
+        assertEquals("three", subStrings[2]);
+        assertEquals("four", subStrings[3]);
+        assertEquals("five", subStrings[4]);
     }
 
     @Test
-    public void testRestoreString4()
-    {
-        fail("Not yet implemented");
-
+    public void testRestoreString3() {
+        manipulatedstring.setString("abc");
+        int[] indices = new int[]{2, 0, 1};
+        String restoreString = manipulatedstring.restoreString(indices);
+        assertEquals("bca", restoreString);
     }
 
     @Test
-    public void testRestoreString5()
-    {
-        fail("Not yet implemented");
-
+    public void testRestoreString4() {
+        manipulatedstring.setString("hello");
+        int[] indices = new int[]{4, 3, 2, 1, 0};
+        String restoreString = manipulatedstring.restoreString(indices);
+        assertEquals("olleh", restoreString);
     }
-
-}
+}
\ No newline at end of file