coding test/leetCode

[leetCode/JS] 2047. Number of Valid Words in a Sentence

쭘봉 2022. 11. 24. 01:09

문제 설명

A sentence consists of lowercase letters ('a' to 'z'), digits ('0' to '9'), hyphens ('-'), punctuation marks ('!', '.', and ','), and spaces (' ') only. Each sentence can be broken down into one or more tokens separated by one or more spaces ' '.

A token is a valid word if all three of the following are true:

  • It only contains lowercase letters, hyphens, and/or punctuation (no digits).
  • There is at most one hyphen '-'. If present, it must be surrounded by lowercase characters ("a-b" is valid, but "-ab" and "ab-" are not valid).
  • There is at most one punctuation mark. If present, it must be at the end of the token ("ab,", "cd!", and "." are valid, but "a!b" and "c.," are not valid).

Examples of valid words include "a-b.", "afad", "ba-c","a!", and "!".

Given a string sentence, return the number of valid words in sentence.



입출력 예

Example 1:

Input: sentence = "cat and dog"
Output: 3
Explanation: The valid words in the sentence are "cat", "and", and "dog".


Example 2:

Input: sentence = "!this 1-s b8d!"
Output: 0
Explanation: There are no valid words in the sentence.
"!this" is invalid because it starts with a punctuation mark.
"1-s" and "b8d" are invalid because they contain digits.


Example 3:

Input: sentence = "alice and bob are playing stone-game10"
Output: 5
Explanation: The valid words in the sentence are "alice", "and", "bob", "are", and "playing".
"stone-game10" is invalid because it contains digits.



  • 1 <= sentence.length <= 1000
  • sentence only contains lowercase English letters, digits, ' ', '-', '!', '.', and ','.
  • There will be at least 1 token.

내 솔루션

  • 조건 3가지에 대해서 합칠 수 있는건 합치고 혼자 '!', ',', '.' 이렇게 오는거는 따로 빼줬다.
  • 한줄로 하고 싶은데 어떻게 하는지 모르겠다. REGEX 어렵.
var countValidWords = function(sentence) {
  const arr = sentence.trim().split(' ')
  let count = 0;
  for(let i = 0; i < arr.length; i++) {
    if(/^[a-z]+(-[a-z]+)?[\.!,]?$/.test(arr[i]) || /^[\.!,]$/.test(arr[i])) {
  return count;


  • 솔직히 regex 문제들은 Test site 못열면 틀릴 각오 해야하는거 아닌가 싶다.
  • regex 관련 문법들을 다시 공부해봐야하나 너무 어렵다.