Keyboard Row

Description

Given a List of words, return the words that can be typed using letters of alphabet on only one row's of American keyboard like the image below.

 

 

Example:

Input: ["Hello", "Alaska", "Dad", "Peace"]
Output: ["Alaska", "Dad"]

 

Note:

1. You may use one character in the keyboard more than once.
2. You may assume the input string will only contain letters of alphabet.

Solution(javascript)

/**
 * @param {string[]} words
 * @return {string[]}
 */
const findWords = (words) => {
  const firstRow = 'qwertyuiop'
  const secondRow = 'asdfghjkl'
  const thirdRow = 'zxcvbnm'
  const dict = {}
  const generateDict = (d, row, num) => {
    for (c of row) {
      d[c] = num
    }
  }
  generateDict(dict, firstRow, 1)
  generateDict(dict, secondRow, 2)
  generateDict(dict, thirdRow, 3)
  const isSameRow = (word = '') => {
    word = word.toLowerCase()
    let previous = null
    for (c of word) {
      if (previous && dict[c] !== previous) {
        return false
      }
      previous = dict[c]
    }
    return previous
  }
  return words.filter(isSameRow)
}