Package g1001_1100.s1032_stream_of_characters

Class StreamChecker

  • public class StreamChecker
extends Object
    1032 - Stream of Characters.

    Hard

    Design an algorithm that accepts a stream of characters and checks if a suffix of these characters is a string of a given array of strings words.

    For example, if words = ["abc", "xyz"] and the stream added the four characters (one by one) 'a', 'x', 'y', and 'z', your algorithm should detect that the suffix "xyz" of the characters "axyz" matches "xyz" from words.

    Implement the StreamChecker class:

    • StreamChecker(String[] words) Initializes the object with the strings array words.
    • boolean query(char letter) Accepts a new character from the stream and returns true if any non-empty suffix from the stream forms a word that is in words.

    Example 1:

    Input [“StreamChecker”, “query”, “query”, “query”, “query”, “query”, “query”, “query”, “query”, “query”, “query”, “query”, “query”] ["cd", "f", "kl", [“a”], [“b”], [“c”], [“d”], [“e”], [“f”], [“g”], [“h”], [“i”], [“j”], [“k”], [“l”]]

    Output: [null, false, false, false, true, false, true, false, false, false, false, false, true]

    Explanation:

     StreamChecker streamChecker = new StreamChecker(["cd", "f", "kl"]); 
 streamChecker.query("a"); // return False 
 streamChecker.query("b"); // return False 
 streamChecker.query("c"); // return False 
 streamChecker.query("d"); // return True, because 'cd' is in the wordlist 
 streamChecker.query("e"); // return False 
 streamChecker.query("f"); // return True, because 'f' is in the wordlist 
 streamChecker.query("g"); // return False 
 streamChecker.query("h"); // return False 
 streamChecker.query("i"); // return False 
 streamChecker.query("j"); // return False 
 streamChecker.query("k"); // return False 
 streamChecker.query("l"); // return True, because 'kl' is in the wordlist

    Constraints:

    • 1 <= words.length <= 2000
    • 1 <= words[i].length <= 2000
    • words[i] consists of lowercase English letters.
    • letter is a lowercase English letter.
    • At most 4 * 104 calls will be made to query.

    • Constructor Detail

      • StreamChecker

        public StreamChecker​(String[] words)

    • Method Detail

      • insert

        public void insert​(String s)

      • query

        public boolean query​(char letter)