Create 2785-sort-vowels-in-a-string.java

Author: sanajitjana

Medium/2785-sort-vowels-in-a-string.java

@@ -0,0 +1,85 @@
+/**
+ * Problem: Sort Vowels in a String
+ * LeetCode Link: https://leetcode.com/problems/sort-vowels-in-a-string/
+ * 
+ * Given a string s, sort only the vowels in ascending order and keep other characters in place.
+ * 
+ * Approach 1:
+ * - Extract vowels by checking "AEIOUaeiou".indexOf(c).
+ * - Sort the extracted vowels.
+ * - Rebuild the string by replacing vowels in order.
+ * 
+ * Approach 2:
+ * - Use a Set<Character> of vowels for O(1) lookup.
+ * - Extract vowels into a list.
+ * - Sort the list.
+ * - Reconstruct the string by replacing vowels from the sorted list.
+ * 
+ * Time Complexity (both approaches): O(n log n)
+ *   - O(n) to extract vowels.
+ *   - O(k log k) to sort vowels (k ≤ n).
+ *   - O(n) to rebuild the string.
+ * 
+ * Space Complexity (both approaches): O(n)  
+ *   For storing the extracted vowels and the result string.
+ */
+
+class Solution {
+
+    // Approach 1
+    public String sortVowelsApproach1(String s) {
+        List<Character> vowels = new ArrayList<>();
+        
+        // Extract vowels
+        for (char c : s.toCharArray()) {
+            if ("AEIOUaeiou".indexOf(c) != -1) {
+                vowels.add(c);
+            }
+        }
+
+        // Sort vowels
+        Collections.sort(vowels);
+
+        // Rebuild string with sorted vowels
+        StringBuilder result = new StringBuilder();
+        int vIndex = 0;
+        for (char c : s.toCharArray()) {
+            if ("AEIOUaeiou".indexOf(c) != -1) {
+                result.append(vowels.get(vIndex++));
+            } else {
+                result.append(c);
+            }
+        }
+
+        return result.toString();
+    }
+
+    // Approach 2
+    public String sortVowelsApproach2(String s) {
+        Set<Character> vowels = Set.of('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U');
+        List<Character> extractedVowels = new ArrayList<>();
+
+        // Extract vowels
+        for (char c : s.toCharArray()) {
+            if (vowels.contains(c)) {
+                extractedVowels.add(c);
+            }
+        }
+
+        // Sort vowels
+        Collections.sort(extractedVowels);
+
+        // Rebuild string with sorted vowels
+        StringBuilder sb = new StringBuilder();
+        int index = 0;
+        for (char c : s.toCharArray()) {
+            if (vowels.contains(c)) {
+                sb.append(extractedVowels.get(index++));
+            } else {
+                sb.append(c);
+            }
+        }
+
+        return sb.toString();
+    }
+}