LeetCode: Keyboard Row Solution

Approach

Create a hash table with key-value pair of character-row (eg. q->0, a->1, z-2)

Map each word's characters to the relevant rows and choose the one that only created from one row

1qsd -> 011
2asd -> 111

Use set for faster check

1qsdx -> 0112 -> Set(0, 1, 2) -> invalid
2asdf -> 1111 -> Set(1)       -> valid

Implementation

1var findWords = function (words) {
2  const rowChars = ["qwertyuiop", "asdfghjkl", "zxcvbnm"]
3  const charRowMap = rowChars.reduce((map, row, rowIndex) => {
4    for (const char of row) {
5      map[char] = rowIndex
6    }
7    return map
8  }, {})
9
10  return words.filter(word => {
11    const set = new Set()
12    for (const char of word.toLowerCase()) {
13      set.add(charRowMap[char])
14    }
15    return set.size === 1
16  })
17}