In an alien language, surprisingly they also use english lowercase letters, but possibly in a different order. The order of the alphabet is some permutation of lowercase letters.

Given a sequence of words written in the alien language, and the order

Example 1:

Input: words = ["hello","leetcode"], order = "hlabcdefgijkmnopqrstuvwxyz"
Output: true
Explanation: As 'h' comes before 'l' in this language, then the sequence is sorted.
 

Example 2:

Input: words = ["word","world","row"], order = "worldabcefghijkmnpqstuvxyz"
Output: false
Explanation: As 'd' comes after 'l' in this language, then words[0] > words[1], hence the sequence is unsorted.

Example 3:

Input: words = ["apple","app"], order = "abcdefghijklmnopqrstuvwxyz"
Output: false
Explanation: The first three characters "app" match, and the second string is shorter (in size.) According to lexicographical rules "apple" > "app", because 'l' > '∅', where '∅' is defined as the blank character which is less than any other character (More info).
 

Note:

1. 1 <= words.length <= 100
2. 1 <= words[i].length <= 20
3. order.length == 26
4. All characters in words[i] and order are english lowercase letters.

某種外星語也使用英文小寫字母，但可能順序 order 不同。字母表的順序（order）是一些小寫字母的排列。

給定一組用外星語書寫的單詞 words，以及其字母表的順序 order，只有當給定的單詞在這種外星語中按字典序排列時，返回 true；否則，返回 false。

示例 1：

輸入：words = ["hello","leetcode"], order = "hlabcdefgijkmnopqrstuvwxyz"
輸出：true
解釋：在該語言的字母表中，'h' 位於 'l' 之前，所以單詞序列是按字典序排列的。

示例 2：

輸入：words = ["word","world","row"], order = "worldabcefghijkmnpqstuvxyz"
輸出：false
解釋：在該語言的字母表中，'d' 位於 'l' 之後，那麼 words[0] > words[1]，因此單詞序列不是按字典序排列的。

示例 3：

輸入：words = ["apple","app"], order = "abcdefghijklmnopqrstuvwxyz"
輸出：false
解釋：當前三個字元 "app" 匹配時，第二個字串相對短一些，然後根據詞典編纂規則 "apple" > "app"，因為 'l' > '∅'，其中 '∅' 是空白字元，定義為比任何其他字元都小（更多資訊）。

提示：

1. 1 <= words.length <= 100
2. 1 <= words[i].length <= 20
3. order.length == 26
4. 在 words[i] 和 order 中的所有字元都是英文小寫字母。

 1 class Solution {
 2     func isAlienSorted(_ words: [String], _ order: String) -> Bool {
 3         var words = words
 4         var a:[Int] = [Int](repeating:0,count:256)
 5         var i:Int = 0
 6         var j:Int = 0
 7         for i in 0..<order.count
 8         {
 9             a[order[i].ascii] = i
10         }
11         for i in 0..<words.count
12         {
13             for j in 0..<words[i].count
14             {
15                 //a:97
16                 words[i][j] = (a[words[i][j].ascii] + 97).ASCII
17             }
18         }
19          for i in 0..<(words.count - 1)
20         {
21             if words[i] > words[i+1]
22             {
23                 return false
24             }
25         }
26         return true
27     }
28 }
29 extension String {        
30     //subscript函式可以檢索陣列中的值
31     //直接按照索引方式擷取指定索引的字元
32     subscript (_ i: Int) -> Character {
33         //讀取字元
34         get {return self[index(startIndex, offsetBy: i)]}
35         
36         //修改字元
37         set
38         {
39             var str:String = self
40             var index = str.index(startIndex, offsetBy: i)
41             str.remove(at: index)
42             str.insert(newValue, at: index)
43             self = str
44         }
45     }
46 }
47 
48 //Character擴充套件方法  
49 extension Character  
50 {  
51   //屬性：ASCII整數值(定義小寫為整數值)
52    var ascii: Int {
53         get {
54             let s = String(self).unicodeScalars
55             return Int(s[s.startIndex].value)
56         }
57     }
58 }
59 
60 //Int擴充套件方法  
61 extension Int
62 {
63     //屬性：ASCII值(定義大寫為字元值)
64     var ASCII:Character 
65     {
66         get {return Character(UnicodeScalar(self)!)}
67     }
68 }