[Swift]LeetCode936. 戳印序列 | Stamping The Sequence

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➤微信公衆號：山青詠芝（shanqingyongzhi）
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You want to form a target string of lowercase letters.

At the beginning, your sequence is target.length '?' marks.  You also have a stamp of lowercase letters.

On each turn, you may place the stamp over the sequence, and replace every letter in the sequence with the corresponding letter from the stamp.  You can make up to 10 * target.length turns.

For example, if the initial sequence is "?????", and your stamp is "abc",  then you may make "abc??", "?abc?", "??abc" in the first turn.  (Note that the stamp must be fully contained in the boundaries of the sequence in order to stamp.)

If the sequence is possible to stamp, then return an array of the index of the left-most letter being stamped at each turn.  If the sequence is not possible to stamp, return an empty array.

For example, if the sequence is "ababc", and the stamp is "abc", then we could return the answer [0, 2], corresponding to the moves "?????" -> "abc??" -> "ababc".

Also, if the sequence is possible to stamp, it is guaranteed it is possible to stamp within 10 * target.length moves.  Any answers specifying more than this number of moves will not be accepted.

Example 1:

Input: stamp = "abc", target = "ababc" Output: [0,2] ([1,0,2] would also be accepted as an answer, as well as some other answers.) 

Example 2:

Input: stamp = "abca", target = "aabcaca" Output: [3,0,1]

Note:

1. 1 <= stamp.length <= target.length <= 1000
2. stamp and target only contain lowercase letters.

---

你想要用小寫字母組成一個目標字符串 target。 

開始的時候，序列由 target.length 個 '?' 記號組成。而你有一個小寫字母印章 stamp。

在每一個回合，你能夠將印章放在序列上，並將序列中的每一個字母替換爲印章上的相應字母。你最多能夠進行 10 * target.length  個回合。

舉個例子，若是初始序列爲 "?????"，而你的印章 stamp 是 "abc"，那麼在第一回合，你能夠獲得 "abc??"、"?abc?"、"??abc"。（請注意，印章必須徹底包含在序列的邊界內才能蓋下去。）

若是能夠印出序列，那麼返回一個數組，該數組由每一個回合中被印下的最左邊字母的索引組成。若是不能印出序列，就返回一個空數組。

例如，若是序列是 "ababc"，印章是 "abc"，那麼咱們就能夠返回與操做 "?????" -> "abc??" -> "ababc" 相對應的答案 [0, 2]；

另外，若是能夠印出序列，那麼須要保證能夠在 10 * target.length 個回合內完成。任何超過此數字的答案將不被接受。

示例 1：

輸入：stamp = "abc", target = "ababc"
輸出：[0,2]
（[1,0,2] 以及其餘一些可能的結果也將做爲答案被接受）

示例 2：

輸入：stamp = "aabcaca", target = "abca"
輸出：[3,0,1]

提示：

1. 1 <= stamp.length <= target.length <= 1000
2. stamp 和 target 只包含小寫字母。

---

52ms

 1 class Solution {
 2     func movesToStamp(_ stamp: String, _ target: String) -> [Int] {
 3         //轉換爲數組
 4         var t:[Character] = target.toCharArray()
 5         var s:[Character] = stamp.toCharArray()
 6         
 7         var route:[Int] = [Int]()
 8         let num:Int = t.count - s.count + 1
 9         var done:[Bool] = [Bool](repeating:false,count:num)
10         while(true)
11         {
12             var up:Bool = false
13             for i in 0..<num
14             {
15                 if done[i] {continue}
16                 var cor = cors(s, t, i)
17                 if cor == 1
18                 {
19                     route.insert(i, at: 0)
20                     for j in 0..<s.count
21                     {
22                         t[j+i] = "."
23                     }
24                     up = true
25                     done[i] = true
26                 }
27                 else if cor == 2
28                 {
29                     done[i] = true
30                 }
31             }
32             if !up {break}
33         }
34         for i in 0..<t.count
35         {
36             if t[i] != "."
37             {
38                 return []
39             }
40         }
41         var ret:[Int] = [Int](repeating:0,count:route.count)
42         var p:Int = 0
43         for x in route
44         {
45             ret[p++] = x
46         }
47         return ret
48     }
49     
50     func cors(_ s:[Character],_ t:[Character],_ f:Int) -> Int
51     {
52         var ex:Int = 0
53         for i in 0..<s.count
54         {
55             if t[i+f] == "." {continue}
56             ex = 1
57             if s[i] != t[i+f] {return 0}
58         }
59         if ex == 0 {return 2}
60         return 1
61     }
62 }
63 
64 extension String {
65     //轉換爲字符數組
66     func toCharArray() -> [Character]
67     {
68         var chars:[Character] = [Character]()
69         for char in self.characters
70         {
71             chars.append(char)
72         }
73         return chars
74     }
75 }
76 /*擴展Int類，實現自增++運算符*/
77 extension Int{
78     //後綴++:先執行表達式後再自增
79     static postfix func ++(num:inout Int) -> Int {
80         //輸入輸出參數num
81         let temp = num
82         //num加1
83         num += 1
84         //返回加1前的數值
85         return temp
86     }
87 }