diff --git a/src/main/java/g3101_3200/s3136_valid_word/Solution.java b/src/main/java/g3101_3200/s3136_valid_word/Solution.java
index c4c41dd46..72b6e38c1 100644
--- a/src/main/java/g3101_3200/s3136_valid_word/Solution.java
+++ b/src/main/java/g3101_3200/s3136_valid_word/Solution.java
@@ -1,35 +1,26 @@
 package g3101_3200.s3136_valid_word;
 
-// #Easy #String #2024_05_07_Time_1_ms_(99.39%)_Space_41.9_MB_(59.69%)
+// #Easy #String #2025_07_15_Time_1_ms_(99.12%)_Space_42.10_MB_(62.25%)
 
 public class Solution {
     public boolean isValid(String word) {
         if (word.length() < 3) {
             return false;
         }
-        if (word.contains("@") || word.contains("#") || word.contains("$")) {
-            return false;
-        }
-        char[] vowels = {'a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'};
-        char[] consonants = {
-            'b', 'c', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'n', 'p', 'q', 'r', 's', 't', 'v',
-            'w', 'x', 'y', 'z', 'B', 'C', 'D', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'Q',
-            'R', 'S', 'T', 'V', 'W', 'X', 'Y', 'Z'
-        };
-        boolean flag1 = false;
-        boolean flag2 = false;
-        for (char c : vowels) {
-            if (word.indexOf(c) != -1) {
-                flag1 = true;
-                break;
-            }
-        }
-        for (char c : consonants) {
-            if (word.indexOf(c) != -1) {
-                flag2 = true;
-                break;
+        boolean hasVowel = false;
+        boolean hasConsonant = false;
+        for (char c : word.toCharArray()) {
+            if (Character.isLetter(c)) {
+                char ch = Character.toLowerCase(c);
+                if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
+                    hasVowel = true;
+                } else {
+                    hasConsonant = true;
+                }
+            } else if (!Character.isDigit(c)) {
+                return false;
             }
         }
-        return flag1 && flag2;
+        return hasVowel && hasConsonant;
     }
 }
diff --git a/src/test/java/g3101_3200/s3136_valid_word/SolutionTest.java b/src/test/java/g3101_3200/s3136_valid_word/SolutionTest.java
index 8fe1dc8de..3b72b4cf0 100644
--- a/src/test/java/g3101_3200/s3136_valid_word/SolutionTest.java
+++ b/src/test/java/g3101_3200/s3136_valid_word/SolutionTest.java
@@ -20,4 +20,72 @@ void isValid2() {
     void isValid3() {
         assertThat(new Solution().isValid("a3$e"), equalTo(false));
     }
+
+    @Test
+    void isValid4() {
+        assertThat(new Solution().isValid("a"), equalTo(false));
+        assertThat(new Solution().isValid("ab"), equalTo(false));
+        assertThat(new Solution().isValid("1"), equalTo(false));
+        assertThat(new Solution().isValid("1a"), equalTo(false));
+        assertThat(new Solution().isValid(""), equalTo(false));
+    }
+
+    @Test
+    void isValid5() {
+        assertThat(new Solution().isValid("aei"), equalTo(false));
+        assertThat(new Solution().isValid("AEI"), equalTo(false));
+        assertThat(new Solution().isValid("Aei"), equalTo(false));
+        assertThat(new Solution().isValid("uuu"), equalTo(false));
+    }
+
+    @Test
+    void isValid6() {
+        assertThat(new Solution().isValid("bcdfg"), equalTo(false));
+        assertThat(new Solution().isValid("BCD"), equalTo(false));
+        assertThat(new Solution().isValid("xyz"), equalTo(false));
+        assertThat(new Solution().isValid("QWRTY"), equalTo(false));
+    }
+
+    @Test
+    void isValid7() {
+        assertThat(new Solution().isValid("abc"), equalTo(true));
+        assertThat(new Solution().isValid("bac"), equalTo(true));
+        assertThat(new Solution().isValid("AeIbcD"), equalTo(true));
+        assertThat(new Solution().isValid("tree"), equalTo(true));
+        assertThat(new Solution().isValid("skyE"), equalTo(true));
+    }
+
+    @Test
+    void isValid8() {
+        assertThat(new Solution().isValid("a1b2c"), equalTo(true));
+        assertThat(new Solution().isValid("1a2b"), equalTo(true));
+        assertThat(new Solution().isValid("b2c4e"), equalTo(true));
+        assertThat(new Solution().isValid("123"), equalTo(false));
+    }
+
+    @Test
+    void isValid10() {
+        assertThat(new Solution().isValid("a#b"), equalTo(false));
+        assertThat(new Solution().isValid("@ab"), equalTo(false));
+        assertThat(new Solution().isValid("ab!"), equalTo(false));
+        assertThat(new Solution().isValid("c_d"), equalTo(false));
+        assertThat(new Solution().isValid("a.b"), equalTo(false));
+        assertThat(new Solution().isValid("abc "), equalTo(false));
+    }
+
+    @Test
+    void isValid11() {
+        assertThat(new Solution().isValid("AbC"), equalTo(true));
+        assertThat(new Solution().isValid("BacE1"), equalTo(true));
+        assertThat(new Solution().isValid("zEi"), equalTo(true));
+    }
+
+    @Test
+    void isValid12() {
+        assertThat(new Solution().isValid("a1b"), equalTo(true));
+        assertThat(new Solution().isValid("ab1"), equalTo(true));
+        assertThat(new Solution().isValid("1ab"), equalTo(true));
+        assertThat(new Solution().isValid("1a"), equalTo(false));
+        assertThat(new Solution().isValid("1b"), equalTo(false));
+    }
 }