Improved 3456

Author: javadev

src/main/java/g3401_3500/s3456_find_special_substring_of_length_k/Solution.java

@@ -1,36 +1,45 @@
 package g3401_3500.s3456_find_special_substring_of_length_k;
 
-// #Easy #2025_02_16_Time_1_ms_(100.00%)_Space_42.04_MB_(100.00%)
+// #Easy #2025_02_16_Time_0_ms_(100.00%)_Space_42.05_MB_(100.00%)
 
 public class Solution {
     public boolean hasSpecialSubstring(String s, int k) {
-        // 🚫 If string is smaller than k, no valid substring exists
-        if (s.length() < k) {
-            return false;
+        if (s.length() == k) {
+            if (k == 1) {
+                return true;
+            }
+            for (int i = 0; i < k - 1; i++) {
+                if (s.charAt(i) != s.charAt(i + 1)) {
+                    return false;
+                }
+            }
+            return true;
         }
-        // 🔍 Iterate through all possible substrings of length k
-        for (int i = 0; i <= s.length() - k; i++) {
-            // 🧮 Count consecutive identical characters
-            int count = 1;
-            // ✅ Check if all k characters in the substring are the same
-            for (int j = i; j < i + k - 1; j++) {
-                if (s.charAt(j) == s.charAt(j + 1)) {
-                    // ➕ Increase count if consecutive characters are the same
-                    count++;
-                } else {
-                    // ❌ Break if mismatch occurs
+        int start = 0;
+        int end = k;
+        while (end <= s.length()) {
+            boolean flag = false;
+            for (int i = start; i < end - 1; i++) {
+                if (s.charAt(i) != s.charAt(i + 1)) {
+                    start++;
+                    end++;
+                    flag = true;
                     break;
                 }
             }
-            // 🔎 Ensure the substring is not part of a larger group
-            if (count == k
-                    && (i == 0 || s.charAt(i - 1) != s.charAt(i))
-                    && (i + k == s.length() || s.charAt(i + k) != s.charAt(i))) {
-                // 🎯 Found a valid special substring
+            if (flag) {
+                continue;
+            }
+            if (start - 1 >= 0 && s.charAt(start) == s.charAt(start - 1)) {
+                start++;
+                end++;
+            } else if (end < s.length() && s.charAt(end) == s.charAt(end - 1)) {
+                start++;
+                end++;
+            } else {
                 return true;
             }
         }
-        // ❌ No valid substring found
         return false;
     }
 }