Methods

1) void storeWord(String word, String meaning)

• Insert or update the mapping (word → meaning).
• Both word and meaning will be lowercase and non blank
• 'meaning' will overwrite any older 'meaning' if one already exists for 'word'.
• word contains only lowercase letters [a-z], space ' ', hyphen '-'
• word will never contain the dot (.) character.

2) String getMeaning(String word)

• Return the meaning for word if it exists, otherwise return the empty string "".
• Constraints: word is lowercase, non-blank

3) List[String] searchWords(String prefix, int n)

• Return up to n words that start with prefix, sorted lexicographically (ascending).
• If fewer than n matches exist, return all matches.
• Constraints: prefix is non-blank, lowercase, 1 ≤ n .

4) boolean exists(String word)

• Return true if at least one stored word matches the pattern in word, else false.
• The pattern may include one or more dots ., where each . matches exactly one letter (a-z, space, hyphen) in 'word'.
• Non-dot characters must match exactly, pattern length must equal candidate word length.
• Stored words never contain ., only the query pattern may include dots.

Examples

Assume the dictionary starts empty.

1. Store, Overwrite, and Fetch
   • storeWord("apple", "a fruit")
   • getMeaning("apple") → "a fruit"
   • storeWord("apple", "sweet fruit") (overwrites)
   • getMeaning("apple") → "sweet fruit"
   • getMeaning("apples") → "" (no such word)
2. Prefix Search with Sorting and Limit
   • Insert:
     • storeWord("app", "short for application")
     • storeWord("apple", "sweet fruit")
     • storeWord("apply", "make a formal request")
     • storeWord("apt", "suitable")
     • storeWord("banana", "yellow fruit")
   • searchWords("ap", 3) → ["app", "apple", "apply"]
   • searchWords("app", 10) → ["app", "apple", "apply"]
   • searchWords("b", 2) → ["banana"]
3. Existence with . Wildcards
   • Suppose stored words: {"cat","cap","caps","map","man","many"}
   • exists("cat") → true
   • exists("c.t") → true (e.g., matches "cat")
   • exists("ca.") → true (matches "cat","cap")
   • exists("..p") → true (matches "cap","map")
   • exists("c..s") → true (matches "caps")
   • exists("....") → true (matches "caps")
   • exists("c..") → true (matches "cat","cap")
   • exists("c.") → false (no two-letter words starting with c)
   • exists("...y") → true (matches "many")