diff --git a/src/CountAsterisks2315.java b/src/CountAsterisks2315.java
deleted file mode 100644
index 1363e59..0000000
--- a/src/CountAsterisks2315.java
+++ /dev/null
@@ -1,20 +0,0 @@
-public class CountAsterisks2315 {
-    public int countAsterisks(String s) {
-        String[] words = s.split("\\|");
-        int res = 0;
-        for (int i = 0; i < words.length; i = i + 2) {
-            for (int j = 0; j < words[i].length(); j++) {
-                if (words[i].charAt(j) == '*') {
-                    res++;
-                }
-            }
-        }
-        return res;
-    }
-
-    public static void main(String[] args) {
-        String s = "l|*e*et|c**o|*de|";
-        // 2
-        System.out.println(new CountAsterisks2315().countAsterisks(s));
-    }
-}
diff --git a/src/main/java/com/leetcode/easy/CountAsterisks2315.java b/src/main/java/com/leetcode/easy/CountAsterisks2315.java
new file mode 100644
index 0000000..c395850
--- /dev/null
+++ b/src/main/java/com/leetcode/easy/CountAsterisks2315.java
@@ -0,0 +1,29 @@
+// Tags: String
+package com.leetcode.easy;
+
+public class CountAsterisks2315 {
+    /**
+     * Let n = s.length() and m = words.length (the number of split segments), where m <= n + 1.
+     * Time complexity: O(n)
+     * Breakdown:
+     * - Split operation: s.split("\\|") iterates through the entire string - O(n)
+     * - Outer loop: Iterates through about half of the segments - O(m/2) = O(m)
+     * - Inner loop: Across all iterations, the total number of characters checked is at most n - O(n)
+     * Overall: O(n)
+     * <p>
+     * Space complexity: O(n)
+     * - Array storage: String[] words holds m references to substrings whose total length is O(n) - O(n)
+     */
+    public int countAsterisks(String s) {
+        String[] words = s.split("\\|");
+        int res = 0;
+        for (int i = 0; i < words.length; i = i + 2) {
+            for (int j = 0; j < words[i].length(); j++) {
+                if (words[i].charAt(j) == '*') {
+                    res++;
+                }
+            }
+        }
+        return res;
+    }
+}
diff --git a/src/test/java/com/leetcode/easy/CountAsterisks2315Test.java b/src/test/java/com/leetcode/easy/CountAsterisks2315Test.java
new file mode 100644
index 0000000..d2129b0
--- /dev/null
+++ b/src/test/java/com/leetcode/easy/CountAsterisks2315Test.java
@@ -0,0 +1,42 @@
+package com.leetcode.easy;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class CountAsterisks2315Test {
+    private CountAsterisks2315 solution;
+
+    @BeforeEach
+    void setUp() {
+        solution = new CountAsterisks2315();
+    }
+
+    @Test
+    void testCountAsterisks_Example1() {
+        String s = "l|*e*et|c**o|*de|";
+
+        int result = solution.countAsterisks(s);
+
+        assertEquals(2, result);
+    }
+
+    @Test
+    void testCountAsterisks_Example2() {
+        String s = "iamprogrammer";
+
+        int result = solution.countAsterisks(s);
+
+        assertEquals(0, result);
+    }
+
+    @Test
+    void testCountAsterisks_Example3() {
+        String s = "yo|uar|e**|b|e***au|tiful";
+
+        int result = solution.countAsterisks(s);
+
+        assertEquals(5, result);
+    }
+}