Find the length of the longest substring T of a given string (consists of lowercase letters only) such that every character in T appears no less than k times.
Example 1:
Input: s = "aaabb",k = 3 Output: 3 The longest substring is "aaa",as ‘a‘ is repeated 3 times.
Example 2:
Input: s = "ababbc",k = 2 Output: 5 The longest substring is "ababb",as ‘a‘ is repeated 2 times and ‘b‘ is repeated 3 times.
找到给定字符串（由小写字符组成）中的最长子串 T ， 要求 T 中的每一字符出现次数都不少于 k 。输出 T 的长度。
示例 1:
输入: s = "aaabb",k = 3 输出: 3 最长子串为 "aaa" ，其中 ‘a‘ 重复了 3 次。
示例 2:
输入: s = "ababbc",k = 2 输出: 5 最长子串为 "ababb" ，其中 ‘a‘ 重复了 2 次， ‘b‘ 重复了 3 次。
16ms
1 class@H_502_46@ Solution { 2 func longestSubstring(_ s: String,_ k: Int) ->@H_502_46@ Int { 3 guard s.count > 0 else@H_502_46@ { 4 return 0 5 @H_502_46@ } 6 7 guard k > 0 else@H_502_46@ { 8 return@H_502_46@ s.count 9 @H_502_46@ } 10 11 var result =@H_502_46@ Int.min 12 var sArray = s.map{ String($0@H_502_46@) } 13 14 func splitString(string@H_502_46@: [String]) { 15 guard string.count > 0 else@H_502_46@ { 16 return 17 @H_502_46@ } 18 var memo =@H_502_46@ [String: Int]() 19 var invalidChar =@H_502_46@ [String]() 20 for i in 0..<string@H_502[email protected] { 21 memo[string[i]] = memo[string[i],default:0] + 1 22 @H_502_46@ } 23 24 var candidates =@H_502_46@ [[String]]() 25 var last = -1 26 var i = 0 27 while i < string@H_502[email protected] { 28 if memo[string[i]]! <@H_502_46@ k { 29 if i <= last + 1@H_502_46@ { 30 last =@H_502_46@ i 31 i += 1 32 continue 33 } else@H_502_46@ { 34 candidates.append(Array(string[last + 1..<@H_502_46@i])) 35 last =@H_502_46@ i 36 @H_502_46@ } 37 @H_502_46@ } 38 i += 1 39 @H_502_46@ } 40 41 if last < string.count - 1@H_502_46@{ 42 candidates.append(Array(string[last + 1..<string@H_502[email protected]])) 43 @H_502_46@ } 44 45 if last == -1@H_502_46@ { 46 result = max(string@H_502[email protected],result) 47 return 48 @H_502_46@ } 49 50 for c in@H_502_46@ candidates { 51 splitString(string@H_502_46@:c) 52 @H_502_46@ } 53 @H_502_46@ } 54 55 splitString(string@H_502_46@:sArray) 56 return result == Int.min ? 0@H_502_46@ : result 57 @H_502_46@ } 58 }
20ms
1 class@H_502_46@ Solution { 2 func longestSubstring(_ s: String,_ k: Int) ->@H_502_46@ Int { 3 return helper(Array(s),0@H_502_46@,s.count,k) 4 @H_502_46@ } 5 6 func helper(_ s: [Character],_ left: Int,_ right: Int,_ k: Int) ->@H_502_46@ Int { 7 guard right - left >= k else { return 0@H_502_46@ } 8 var counts =@H_502_46@ [Character: Int]() 9 for char in s[left..<@H_502_46@right] { 10 counts[char] = (counts[char] ?? 0) + 1 11 @H_502_46@ } 12 13 for i in left..<right where counts[s[i]]! <@H_502_46@ k { 14 var j = i + 1 15 while j < right && counts[s[j]]! < k { j += 1@H_502_46@ } 16 return@H_502_46@ max(helper(s,left,i,k),helper(s,j,right,k)) 17 @H_502_46@ } 18 return right -@H_502_46@ left 19 @H_502_46@ } 20 }
52ms
1 class@H_502_46@ Solution { 2 func longestSubstring(_ s: String,_ k: Int) ->@H_502_46@ Int { 3 var arr =@H_502_46@ Array(s) 4 var cmap:[Character:Int] =@H_502_46@ [:] 5 6 if s.length == 0@H_502_46@ { 7 return 0 8 @H_502_46@ } 9 10 for c in@H_502_46@ arr { 11 if cmap[c] ==@H_502_46@ nil { 12 cmap[c] = 0 13 @H_502_46@ } 14 cmap[c] = cmap[c]! + 1 15 @H_502_46@ } 16 17 var leastfreq = arr.count+1 18 var leastfreqchar:Character? =@H_502_46@ nil 19 for (letter,count) in@H_502_46@ cmap { 20 if count <@H_502_46@ leastfreq { 21 leastfreq =@H_502_46@ count 22 leastfreqchar =@H_502_46@ letter 23 @H_502_46@ } 24 @H_502_46@ } 25 26 if leastfreq >=@H_502_46@ k { 27 return@H_502_46@ s.count 28 @H_502_46@ } 29 30 var begin = 0 31 var maxsofar = 0 32 for i in 0@H_502[email protected] { 33 if i == arr.count || arr[i] ==@H_502_46@ leastfreqchar { 34 let tmp = Array(arr[begin..<@H_502_46@i]) 35 let tmps:String =@H_502_46@ String(tmp) 36 maxsofar =@H_502_46@ max(maxsofar,longestSubstring(tmps,k)) 37 begin = i+1 38 @H_502_46@ } 39 @H_502_46@ } 40 41 return@H_502_46@ maxsofar 42 @H_502_46@ } 43 }
56ms
1 class@H_502_46@ Solution { 2 func longestSubstring(_ s: String,_ k: Int) ->@H_502_46@ Int { 3 if k <= 1 { return@H_502_46@ s.count } 4 5 let array =@H_502_46@ [Character](s) 6 var dict =@H_502_46@ [Character: Int]() 7 for c in@H_502_46@ array { 8 if let count =@H_502_46@ dict[c] { 9 dict[c] = count + 1 10 } else@H_502_46@ { 11 dict[c] = 1 12 @H_502_46@ } 13 @H_502_46@ } 14 15 var result = 0 16 var separator: Character? =@H_502_46@ nil 17 for key in@H_502_46@ dict.keys { 18 if let count = dict[key],count <@H_502_46@ k { 19 separator =@H_502_46@ key 20 break 21 @H_502_46@ } 22 @H_502_46@ } 23 if let separator =@H_502_46@ separator { 24 let subStringArray =@H_502_46@ s.components(separatedBy: String(separator)) 25 for subString in@H_502_46@ subStringArray { 26 let temp =@H_502_46@ longestSubstring(subString,k) 27 if temp >@H_502_46@ result { 28 result =@H_502_46@ temp 29 @H_502_46@ } 30 @H_502_46@ } 31 } else@H_502_46@ { 32 return@H_502_46@ s.count 33 @H_502_46@ } 34 return@H_502_46@ result 35 @H_502_46@ } 36 }
764ms
1 class@H_502_46@ Solution { 2 func longestSubstring(_ s: String,_ k: Int) ->@H_502_46@ Int { 3 if s.count <@H_502_46@ k { 4 return 0 5 @H_502_46@ } 6 var dict =@H_502_46@ [Character: Int]() 7 var i = 0 8 var j = 0 9 let ss =@H_502_46@ Array(s) 10 var maxLength = 0 11 for k in@H_502_46@ s { 12 dict[k] = (dict[k] ?? 0) + 1 13 @H_502_46@ } 14 let dict2 = dict.filter{$0.value <@H_502_46@ k} 15 if dict2.count == 0@H_502_46@ { 16 return@H_502_46@ s.count 17 @H_502_46@ } 18 while j <@H_502_46@ s.count { 19 if let d =@H_502_46@ dict2[ss[j]] { 20 if d <@H_502_46@ k { 21 let start =@H_502_46@ s.index(s.startIndex,offsetBy: i) 22 let end =@H_502_46@ s.index(s.startIndex,offsetBy: j) 23 let range = start..<@H_502_46@end 24 let subS =@H_502_46@ s[range] 25 maxLength =@H_502_46@ max(maxLength,longestSubstring(String(subS),k)) 26 i = j + 1 27 @H_502_46@ } 28 @H_502_46@ } 29 j += 1 30 @H_502_46@ } 31 let start =@H_502_46@ s.index(s.startIndex,offsetBy: i) 32 let end =@H_502_46@ s.index(s.startIndex,offsetBy: j) 33 let range = start..<@H_502_46@end 34 let subS =@H_502_46@ s[range] 35 maxLength =@H_502_46@ max(maxLength,k)) 36 return@H_502_46@ maxLength 37 @H_502_46@ } 38 }
948ms
1 class@H_502_46@ Solution { 2 func longestSubstring(_ s: String,_ k: Int) ->@H_502_46@ Int { 3 var n:Int =@H_502_46@ s.count 4 var max_idx:Int = 0 5 var res:Int = 0 6 var m:[Int] = [Int](repeating:0,count: 128@H_502_46@) 7 var ok:Bool = true 8 for c in@H_502_46@ s.characters 9 @H_502_46@ { 10 m[c.ascii] += 1 11 @H_502_46@ } 12 for i in 0..<@H_502_46@n 13 @H_502_46@ { 14 if m[s[i].ascii] <@H_502_46@ k 15 @H_502_46@ { 16 res = max(res,longestSubstring(s.subString(max_idx,i -@H_502_46@ max_idx),k)) 17 ok = false 18 max_idx = i + 1 19 @H_502_46@ } 20 @H_502_46@ } 21 return ok ? n : max(res,n -@H_502_46@ max_idx),k)) 22 @H_502_46@ } 23 @H_502_46@} 24 25 @H_502_46@extension String { 26 //subscript函数可以检索数组中的值 27 //直接按照索引方式截取指定索引的字符 28 subscript (_ i: Int) ->@H_502_46@ Character { 29 //读取字符 30 get {return@H_502_46@ self[index(startIndex,offsetBy: i)]} 31 @H_502_46@ } 32 33 // 截取字符串：指定索引和字符数 34 // - begin: 开始截取处索引 35 // - count: 截取的字符数量 36 func subString(_ begin:Int,_ count:Int) ->@H_502_46@ String { 37 let start = self.index(self.startIndex,offsetBy: max(0@H_502_46@,begin)) 38 let end = self.index(self.startIndex,offsetBy: min(self.count,begin +@H_502_46@ count)) 39 return String(self[start..<@H_502_46@end]) 40 @H_502_46@ } 41 @H_502_46@} 42 43 //Character扩展方法 44 @H_502_46@extension Character 45 @H_502_46@{ 46 //属性：ASCII整数值(定义小写为整数值) 47 var@H_502_46@ ascii: Int { 48 get@H_502_46@ { 49 let s =@H_502_46@ String(self).unicodeScalars 50 return@H_502_46@ Int(s[s.startIndex].value) 51 @H_502_46@ } 52 @H_502_46@ } 53 }
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