[Swift]LeetCode38. 報數 | Count and Say

時間 2019-11-11

標籤 swift leetcode38 leetcode 報數 count say 欄目 Swift 简体版

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The count-and-say sequence is the sequence of integers with the first five terms as following:git

1.     1
2.     11
3.     21
4.     1211
5.     111221

1 is read off as "one 1" or 11.
11 is read off as "two 1s" or 21.
21 is read off as "one 2, then one 1" or 1211.github

Given an integer n where 1 ≤ n ≤ 30, generate the nth term of the count-and-say sequence.微信

Note: Each term of the sequence of integers will be represented as a string.app

Example 1:spa

Input: 1
Output: "1"

Example 2:code

Input: 4
Output: "1211"

報數序列是指一個整照其中的整數的順序進數序列，按行報數，獲得下一個數。其前五項以下：htm

1.     1
2.     11
3.     21
4.     1211
5.     111221

1 被讀做 "one 1" ("一個一") , 即 11。
11 被讀做 "two 1s" ("兩個一"）, 即 21。
21 被讀做 "one 2", "one 1" （"一個二" , "一個一") , 即 1211。blog

給定一個正整數 n（1 ≤ n ≤ 30），輸出報數序列的第 n 項。rem

注意：整數順序將表示爲一個字符串。

示例 1:

輸入: 1
輸出: "1"

示例 2:

輸入: 4
輸出: "1211"

12ms

1 class Solution {
2     func countAndSay(_ n: Int) -> String {
3         let ans=["","1","11","21","1211","111221","312211","13112221","1113213211","31131211131221","13211311123113112211","11131221133112132113212221","3113112221232112111312211312113211","1321132132111213122112311311222113111221131221","11131221131211131231121113112221121321132132211331222113112211","311311222113111231131112132112311321322112111312211312111322212311322113212221","132113213221133112132113311211131221121321131211132221123113112221131112311332111213211322211312113211","11131221131211132221232112111312212321123113112221121113122113111231133221121321132132211331121321231231121113122113322113111221131221","31131122211311123113321112131221123113112211121312211213211321322112311311222113311213212322211211131221131211132221232112111312111213111213211231131122212322211331222113112211","1321132132211331121321231231121113112221121321132122311211131122211211131221131211132221121321132132212321121113121112133221123113112221131112311332111213122112311311123112111331121113122112132113213211121332212311322113212221","11131221131211132221232112111312111213111213211231132132211211131221131211221321123113213221123113112221131112311332211211131221131211132211121312211231131112311211232221121321132132211331121321231231121113112221121321133112132112312321123113112221121113122113121113123112112322111213211322211312113211","311311222113111231133211121312211231131112311211133112111312211213211312111322211231131122211311122122111312211213211312111322211213211321322113311213212322211231131122211311123113223112111311222112132113311213211221121332211211131221131211132221232112111312111213111213211231132132211211131221232112111312211213111213122112132113213221123113112221131112311311121321122112132231121113122113322113111221131221","132113213221133112132123123112111311222112132113311213211231232112311311222112111312211311123113322112132113213221133122112231131122211211131221131112311332211211131221131211132221232112111312111213322112132113213221133112132113221321123113213221121113122123211211131221222112112322211231131122211311123113321112131221123113111231121113311211131221121321131211132221123113112211121312211231131122211211133112111311222112111312211312111322211213211321322113311213211331121113122122211211132213211231131122212322211331222113112211","111312211312111322212321121113121112131112132112311321322112111312212321121113122112131112131221121321132132211231131122211331121321232221121113122113121113222123112221221321132132211231131122211331121321232221123113112221131112311332111213122112311311123112112322211211131221131211132221232112111312211322111312211213211312111322211231131122111213122112311311221132211221121332211213211321322113311213212312311211131122211213211331121321123123211231131122211211131221131112311332211213211321223112111311222112132113213221123123211231132132211231131122211311123113322112111312211312111322212321121113122123211231131122113221123113221113122112132113213211121332212311322113212221","3113112221131112311332111213122112311311123112111331121113122112132113121113222112311311221112131221123113112221121113311211131122211211131221131211132221121321132132212321121113121112133221123113112221131112311332111213213211221113122113121113222112132113213221232112111312111213322112132113213221133112132123123112111311222112132113311213211221121332211231131122211311123113321112131221123113112221132231131122211211131221131112311332211213211321223112111311222112132113212221132221222112112322211211131221131211132221232112111312111213111213211231132132211211131221232112111312211213111213122112132113213221123113112221133112132123222112111312211312112213211231132132211211131221131211132221121311121312211213211312111322211213211321322113311213212322211231131122211311123113321112131221123113112211121312211213211321222113222112132113223113112221121113122113121113123112112322111213211322211312113211","13211321322113311213212312311211131122211213211331121321123123211231131122211211131221131112311332211213211321223112111311222112132113213221123123211231132132211231131122211311123113322112111312211312111322111213122112311311123112112322211213211321322113311213212312311211131211131221223113112221131112311332211211131221131211132211121312211231131112311211232221121113122113121113222123211211131211121311121321123113213221121113122123211211131221222112112322211213211321322113311213212312311211131122211213211321322113221321132132211231131122211331121321232221121113122113121122132112311321322112111312211312113221133211322112211213322112311311222113111231133211121312211231131112311211133112111312211213211312111322211231131122111213122112311311222112111331121113112221121113122113121113222112132113213221232112111312111213322112311311222113111221221113122112132113121113222112311311222113111231133221121113311211131122211211131221131112311332211211131221131211132221232112111312111213322112132113213221133112132123123112111311222112132113212231121113112221121113122113121132211332211211131221132213211321322112311311222113111231131112132112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4         return ans[n]
5     }
6 }

16ms

 1 class Solution {
 2     func countAndSay(_ n: Int) -> String {
 3         var num = "1"
 4         if n == 1 {
 5             return "1"
 6         }
 7         for _ in 1..<n {
 8             var newStr = String()
 9             let arrayOfStr = Array(num)
10             var count = 1
11             for i in 0..<arrayOfStr.count {
12                 if i == arrayOfStr.count - 1 {
13                     newStr += "\(count)\(arrayOfStr[i])"
14                 } else {
15                     if arrayOfStr[i] == arrayOfStr[i + 1] {
16                         count += 1
17                     } else {
18                         newStr += "\(count)\(arrayOfStr[i])"
19                         count = 1
20                     }
21                 }
22             }
23             num = newStr
24         }
25         return num
26     }
27 }

16ms

 1 class Solution {
 2     func countAndSay(_ n: Int) -> String {
 3         if (n == 1 || n > 30){
 4             return "1"
 5         }
 6         var resultString:String = ""
 7         let ReadStr = countAndSay(n-1)
 8         var characterArray = [Character](ReadStr)
 9         var repeatTime = 1
10         for i in 0..<characterArray.count {
11             if i == 0 {
12                 if characterArray.count == 1 {
13                     resultString.append(String(repeatTime) + String(characterArray[i]))
14                     repeatTime = 1
15                 }
16                 continue
17             }
18             if characterArray[i] == characterArray[i - 1] {
19                 repeatTime = repeatTime + 1
20             } else {
21                 resultString.append(String(repeatTime) + String(characterArray[i - 1]))
22                 repeatTime = 1
23             }
24             
25             if i == characterArray.count - 1 {
26                 resultString.append(String(repeatTime) + String(characterArray[i]))
27             }
28         }
29         return resultString
30     }
31 }

20ms

 1 class Solution {
 2     func countAndSay(_ n: Int) -> String {
 3           guard n > 0 else{
 4             return ""
 5         }
 6         
 7         var result = "1"
 8         for _ in 1..<n{
 9             let resultCharArray = [Character](result)
10             var count = 1
11             var current = ""
12             for i in 1..<resultCharArray.count{
13                 if resultCharArray[i] == resultCharArray[i - 1]{
14                     count += 1
15                 }else{
16                     current.append("\(count)")
17                     current.append(resultCharArray[i - 1])
18                     count = 1
19                 }
20             }
21             current.append(count == 0 ? "" : "\(count)")
22             current.append(resultCharArray.last!)
23             result = current
24         }
25         return result
26     }
27 }

24ms

 1 class Solution {
 2     func countAndSay(input: String) -> String {
 3         var lastChar: Character?
 4         var count = 0
 5         var result: String = ""
 6         
 7         input.forEach { (char) in
 8             if let myLastChar = lastChar {
 9                 if char != myLastChar {
10                     result = result + String(count) + String(myLastChar)
11                     lastChar = char
12                     count = 1
13                 } else {
14                     count += 1
15                 }
16             } else {
17                 lastChar = char
18                 count = 1
19             }
20         }
21         
22         if let lastChar = lastChar {
23             result = result + String(count) + String(lastChar)
24         }
25         
26         return result
27     }
28     
29     func countAndSay(_ n: Int) -> String {
30         var result = "1"
31         (1..<n).forEach { (_) in
32             result = countAndSay(input: result)
33         }
34         
35         return result
36     }
37 }

24ms

 1 class Solution {
 2     func countAndSay(_ n: Int) -> String {
 3         var resultArray:[Int] = [1]
 4         var tempArray:[Int] = []
 5         var result = ""
 6         for i in 0..<(n - 1) {
 7             var count = 0   //重複數字的計數
 8             var number = -1
 9             var index = 0
10             let length = resultArray.count
11             while index < length {
12                 number = resultArray[index]
13                 for j in index..<length {
14                     if resultArray[j] == number {
15                         count += 1
16                         continue
17                     }
18                     break
19                 }
20                 tempArray.append(count)
21                 tempArray.append(number)
22                 index = index + count
23                 count = 0
24             }
25             resultArray = tempArray
26             tempArray.removeAll()
27         }
28         for i in resultArray {
29             result = result + "\(i)"
30         }
31         return result
32     }
33 }

40ms

 1 /*
 2  理解題意：
 3  n=1時輸出字符串1；
 4  n=2時，數上次字符串中的數值個數，由於上次字符串有1個1，因此輸出11；
 5  n=3時，因爲上次字符是11，有2個1，因此輸出21；
 6  n=4時，因爲上次字符串是21，有1個2和1個1，因此輸出1211。
 7  依次類推
 8  */
 9 
10 import Foundation
11 
12 class Solution {
13     func say(_ say: String) -> String {
14         
15         var chars = Array(say)
16         var count = 1
17         var tmpSay = ""
18         
19         for i in 0..<chars.count {
20             if i < chars.count - 1 && chars[i] == chars[i+1]{
21                 count = count + 1
22             }else{
23                 tmpSay.append("\(count)")
24                 tmpSay.append("\(chars[i])")
25                 count = 1
26             }
27         }
28         return tmpSay
29     }
30     func countAndSay(_ n: Int) -> String {
31         if n == 1 {
32             return "1"
33         }
34         var sayStr = countAndSay(1)
35         
36         for _ in 1..<n {
37             sayStr = say(sayStr)
38         }
39         
40         return sayStr
41     }
42 }

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每一个你不满意的现在，都有一个你没有努力的曾经。