500. Keyboard Row

Author: TBXark

500. Keyboard Row.md

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+# 500. Keyboard Row
+
+### 2017-03-12
+
+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.
+
+![American keyboard](https://leetcode.com/static/images/problemset/keyboard.png)
+
+**Example 1:**
+
+```
+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
+
+```swift
+class Solution {
+    func findWords(_ words: [String]) -> [String] {
+        var res = [String]()
+        let row = ["[qwertyuiop]", "[asdfghjkl]", "[zxcvbnm]"].flatMap({
+            try? RegularExpression(pattern: "^[\($0)]{0,}$", options: [.caseInsensitive])
+        })
+        for str in words {
+            let range = NSRange.init(location: 0, length: str.utf8.count)
+            for regx in row {
+                if regx.matches(in: str, options: [], range: range).count > 0 {
+                    res.append(str)
+                    break
+                }
+            }
+        }
+        return res
+    }
+}
+```
+