Create 0966-vowel-spellchecker.java

Author: sanajitjana

Medium/0966-vowel-spellchecker.java

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+/*
+ * LeetCode Problem: Vowel Spellchecker
+ * https://leetcode.com/problems/vowel-spellchecker/
+ * 
+ * Given a wordlist and a list of queries, return a list of words from wordlist
+ * for each query based on the following rules in order of priority:
+ * 1. Exact match
+ * 2. Case-insensitive match
+ * 3. Vowel error match (replace vowels with any vowel)
+ * 
+ * Approach:
+ * - Store exact words in a HashSet for O(1) look-up.
+ * - Build two maps:
+ *     1. caseInsensitiveMap: maps lowercase words to the original word (first occurrence).
+ *     2. vowelErrorMap: maps vowel-masked lowercase words (vowels replaced by '*') to the original word (first occurrence).
+ * - For each query, try exact match → case-insensitive match → vowel error match → "" (if no match).
+ * 
+ * Time Complexity: O(N + Q * L)
+ *   - N = wordlist length, Q = queries length, L = average word length
+ *   - O(N * L) to process the wordlist and build maps.
+ *   - O(Q * L) to process queries.
+ * 
+ * Space Complexity: O(N * L)
+ *   - Storing words in HashSet and maps.
+ */
+
+import java.util.*;
+
+public class Solution {
+    public String[] spellchecker(String[] wordlist, String[] queries) {
+        Set<String> exactWords = new HashSet<>(Arrays.asList(wordlist));
+        Map<String, String> caseInsensitiveMap = new HashMap<>();
+        Map<String, String> vowelErrorMap = new HashMap<>();
+
+        for (String word : wordlist) {
+            String wordLower = word.toLowerCase();
+            caseInsensitiveMap.putIfAbsent(wordLower, word);
+
+            String wordVowelMasked = maskVowels(wordLower);
+            vowelErrorMap.putIfAbsent(wordVowelMasked, word);
+        }
+
+        String[] ans = new String[queries.length];
+        for (int i = 0; i < queries.length; i++) {
+            String query = queries[i];
+
+            if (exactWords.contains(query)) {
+                ans[i] = query;
+                continue;
+            }
+
+            String queryLower = query.toLowerCase();
+            if (caseInsensitiveMap.containsKey(queryLower)) {
+                ans[i] = caseInsensitiveMap.get(queryLower);
+                continue;
+            }
+
+            String queryVowelMasked = maskVowels(queryLower);
+            if (vowelErrorMap.containsKey(queryVowelMasked)) {
+                ans[i] = vowelErrorMap.get(queryVowelMasked);
+            } else {
+                ans[i] = "";
+            }
+        }
+
+        return ans;
+    }
+
+    private String maskVowels(String str) {
+        StringBuilder sb = new StringBuilder();
+        for (char c : str.toCharArray()) {
+            if ("aeiou".indexOf(c) != -1)
+                sb.append('*');
+            else
+                sb.append(c);
+        }
+        return sb.toString();
+    }
+}