# LeetCode 500. Keyboard Row

## Description

https://leetcode.com/problems/keyboard-row/

Given an array of strings `words`, return the words that can be typed using letters of the alphabet on only one row of American keyboard like the image below.

In the American keyboard:

• the first row consists of the characters `"qwertyuiop"`,
• the second row consists of the characters `"asdfghjkl"`, and
• the third row consists of the characters `"zxcvbnm"`.

Example 1:

```Input: words = ["Hello","Alaska","Dad","Peace"]
```

Example 2:

```Input: words = ["omk"]
Output: []
```

Example 3:

```Input: words = ["adsdf","sfd"]
```

Constraints:

• `1 <= words.length <= 20`
• `1 <= words[i].length <= 100`
• `words[i]` consists of English letters (both lowercase and uppercase).

## Explanation

Check if characters in words are in the same keyboard row.

## Python Solution

``````class Solution:
def findWords(self, words: List[str]) -> List[str]:
results = []

row1 = ["q", "w", "e", "r", "t", "y", "u", "i", "o", "p"]
row2 = ["a", "s", "d", "f", "g", "h", "j", "k", "l"]
row3 = ["z", "x", "c", "v", "b", "n", "m"]

for word in words:
is_same = True
prev_row = 0

for c in word.lower():
row = None

if c in row1:
row = 1
elif c in row2:
row = 2
elif c in row3:
row = 3

if prev_row != 0 and row != prev_row:
is_same = False
break

prev_row = row

if is_same:
results.append(word)

return results
``````
• Time Complexity: O(N).
• Space Complexity: O(N).