[Swift]LeetCode791. 自定義字符串排序 | Custom Sort String

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➤微信公衆號：山青詠芝（shanqingyongzhi）
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S and T are strings composed of lowercase letters. In S, no letter occurs more than once.

S was sorted in some custom order previously. We want to permute the characters of T so that they match the order that S was sorted. More specifically, if x occurs before y in S, then x should occur before y in the returned string.

Return any permutation of T (as a string) that satisfies this property.

Example :
Input: 
S = "cba"
T = "abcd"
Output: "cbad"
Explanation: 
"a", "b", "c" appear in S, so the order of "a", "b", "c" should be "c", "b", and "a". 
Since "d" does not appear in S, it can be at any position in T. "dcba", "cdba", "cbda" are also valid outputs.

Note:

• S has length at most 26, and no character is repeated in S.
• T has length at most 200.
• S and T consist of lowercase letters only.

---

字符串S和 T 只包含小寫字符。在S中，全部字符只會出現一次。

S 已經根據某種規則進行了排序。咱們要根據S中的字符順序對T進行排序。更具體地說，若是S中x在y以前出現，那麼返回的字符串中x也應出如今y以前。

返回任意一種符合條件的字符串T。

示例:
輸入:
S = "cba"
T = "abcd"
輸出: "cbad"
解釋: 
S中出現了字符 "a", "b", "c", 因此 "a", "b", "c" 的順序應該是 "c", "b", "a". 
因爲 "d" 沒有在S中出現, 它能夠放在T的任意位置. "dcba", "cdba", "cbda" 都是合法的輸出。

注意:

• S的最大長度爲26，其中沒有重複的字符。
• T的最大長度爲200。
• S和T只包含小寫字符。

---

Runtime: 8 ms

Memory Usage: 19.8 MB

 1 class Solution {
 2     func customSortString(_ S: String, _ T: String) -> String {
 3         var res:String = String()
 4         var m:[Character:Int] = [Character:Int]()
 5         for c in T
 6         {
 7             m[c,default:0] += 1
 8         }
 9         for c in S
10         {
11             let num:Int = m[c,default:0]
12             for _ in 0..<num
13             {
14                 res.append(c)
15             }
16             m[c,default:0] = 0
17         }
18         for (key,val) in m
19         {
20             for _ in 0..<val
21             {
22                 res.append(key)
23             }
24         }
25         return res
26     }
27 }

---

8ms

 1 class Solution {
 2     func customSortString(_ S: String, _ T: String) -> String {
 3         var tMap: Dictionary<Character, Int> = [:]
 4         for t in T {
 5             if let v = tMap[t] {
 6                 tMap[t] = v + 1
 7             } else {
 8                 tMap[t] = 1
 9             }
10         }
11         
12         var result = ""
13         for s in S {
14             if let v = tMap[s] {
15                 result.append(String(repeating: s, count: v))
16                 tMap.removeValue(forKey: s)
17             }
18         }
19         
20         for k in tMap.keys {
21             result.append(String(repeating: k, count: tMap[k]!))
22         }
23         
24         return result
25     }
26 }

---

24ms

1 class Solution {
2     func customSortString(_ S: String, _ T: String) -> String {
3         let map = S.enumerated().reduce(into: [:]) { $0[$1.1, default: 0] = $1.0 }
4         let character = T.sorted(by: { map[$0, default: Int.max] < map[$1, default: Int.max] })
5         return String(character)
6     }
7 }

---

32ms

 1 class Solution {
 2     static func relativeCode(_ c: Character) -> Int {
 3         return Int(c.unicodeScalars.first!.value - Character("a").unicodeScalars.first!.value)
 4     }
 5     func customSortString(_ S: String, _ T: String) -> String {
 6         var order = [Int](repeating: -1, count: 26)
 7         for (i, s) in S.enumerated() {
 8             order[Solution.relativeCode(s)] = i
 9         }
10         
11         return String(T.sorted {
12             return order[Solution.relativeCode($0)] < order[Solution.relativeCode($1)]
13         })
14     }
15 }