diff --git a/src/RansomNote383.java b/src/RansomNote383.java
deleted file mode 100644
index 21b0395..0000000
--- a/src/RansomNote383.java
+++ /dev/null
@@ -1,23 +0,0 @@
-import java.util.HashMap;
-import java.util.Map;
-
-public class RansomNote383 {
-    public boolean canConstruct(String ransomNote, String magazine) {
-        Map<Character, Integer> countR = new HashMap<>();
-        char[] charsR = ransomNote.toCharArray();
-        for (char c : charsR) {
-            countR.put(c, countR.getOrDefault(c, 0) + 1);
-        }
-        Map<Character, Integer> countM = new HashMap<>();
-        char[] charsM = magazine.toCharArray();
-        for (char c : charsM) {
-            countM.put(c, countM.getOrDefault(c, 0) + 1);
-        }
-        for (Map.Entry<Character, Integer> entry : countR.entrySet()) {
-            if (countM.getOrDefault(entry.getKey(), 0) < entry.getValue()) {
-                return false;
-            }
-        }
-        return true;
-    }
-}
diff --git a/src/main/java/com/leetcode/easy/RansomNote383.java b/src/main/java/com/leetcode/easy/RansomNote383.java
new file mode 100644
index 0000000..639376e
--- /dev/null
+++ b/src/main/java/com/leetcode/easy/RansomNote383.java
@@ -0,0 +1,44 @@
+// Tags: String, Hash Table
+package com.leetcode.easy;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class RansomNote383 {
+    /**
+     * Complexity Analysis:
+     * Let m = length of magazine, n = length of ransom note, k = number of unique characters.
+     * Note: k is at most 26 (constant) for lowercase English letters.
+     * <p>
+     * Time Complexity: O(m)
+     * - Early return when m < n takes O(1)
+     * - Building magazine character frequency map: O(m)
+     * - Building ransom note character frequency map: O(n)
+     * - Validating character counts by iterating ransom note map: O(n)
+     * - Total: O(m) + O(n) + O(n)
+     * - Since we only proceed when m ≥ n, we can simplify: O(m) + O(m) + O(m) = O(m)
+     * <p>
+     * Space Complexity: O(k) or O(1)
+     * - Two hash maps store character frequencies, each with at most k unique characters
+     * - Since k ≤ 26 (constant), can be considered O(1) space
+     */
+    public boolean canConstruct(String ransomNote, String magazine) {
+        if (ransomNote.length() > magazine.length()) {
+            return false;
+        }
+        Map<Character, Integer> countR = new HashMap<>();
+        for (char c : ransomNote.toCharArray()) {
+            countR.put(c, countR.getOrDefault(c, 0) + 1);
+        }
+        Map<Character, Integer> countM = new HashMap<>();
+        for (char c : magazine.toCharArray()) {
+            countM.put(c, countM.getOrDefault(c, 0) + 1);
+        }
+        for (Map.Entry<Character, Integer> entry : countR.entrySet()) {
+            if (countM.getOrDefault(entry.getKey(), 0) < entry.getValue()) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
diff --git a/src/test/java/com/leetcode/easy/RansomNote383Test.java b/src/test/java/com/leetcode/easy/RansomNote383Test.java
new file mode 100644
index 0000000..966d21e
--- /dev/null
+++ b/src/test/java/com/leetcode/easy/RansomNote383Test.java
@@ -0,0 +1,46 @@
+package com.leetcode.easy;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class RansomNote383Test {
+    private RansomNote383 solution;
+
+    @BeforeEach
+    void setUp() {
+        solution = new RansomNote383();
+    }
+
+    @Test
+    void testCanConstruct_Example1() {
+        String ransomNote = "a";
+        String magazine = "b";
+
+        boolean result = solution.canConstruct(ransomNote, magazine);
+
+        assertFalse(result);
+    }
+
+    @Test
+    void testCanConstruct_Example2() {
+        String ransomNote = "aa";
+        String magazine = "ab";
+
+        boolean result = solution.canConstruct(ransomNote, magazine);
+
+        assertFalse(result);
+    }
+
+    @Test
+    void testCanConstruct_Example3() {
+        String ransomNote = "aa";
+        String magazine = "aab";
+
+        boolean result = solution.canConstruct(ransomNote, magazine);
+
+        assertTrue(result);
+    }
+}