[Swift]LeetCode3. 无重复字符的最长子串 | Longest Substring Without Repeating Characters

概述Given a string, find the length of the longest substring without repeating characters. Examples: Given "abcabcbb", the answer is "abc", which the length is 3. Given "bbbbb", the answer is "b", with th

Given a string,find the length of the longest substring without repeating characters.

Examples:

Given "abcabcbb",the answer is "abc",which the length is 3.

Given "bbbbb",the answer is "b",with the length of 1.

Given "pwwkew",the answer is "wke",with the length of 3. Note that the answer must be a substring, "pwke" is a subsequence and not a substring.

 

给定一个字符串，找出不含有重复字符的最长子串的长度。

示例 1:

输入: "abcabcbb"输出: 3 解释: 无重复字符的最长子串是 长度为 3。"abc"，其

示例 2:

输入: "bbbbb"输出: 1解释: 无重复字符的最长子串是 ，其长度为 1。"b"

示例 3:

输入: "pwwkew"输出: 3解释: 无重复字符的最长子串是 ，其长度为 3。     请注意，答案必须是一个子串， 是一个子序列 而不是子串。"wke""pwke"

36ms

 1 class Solution { 2     func lengthOfLongestSubstring(_ s: String) -> Int { 3         var m:[Int] = [Int](repeating: -1,count: 256) 4         var res:Int = 0,left:Int = -1 5         for i in 0..<s.count 6         { 7             let num:Int = s[s.index(s.startIndex,offsetBy: i)].toInt() 8             left = max(left,m[num]) 9             m[num] = i10             res = max(res,i - left)11         }12         return res13     }14 }15 //Character扩展方法  16 extension Character  17 {  18     func toInt() -> Int  19     {  20         var num:Int = Int()21         for scalar in String(self).unicodeScalars  22         {  23             num = Int(scalar.value)  24         }  25         return num  26     }  27 }

20ms

 1 class Solution { 2  func lengthOfLongestSubstring(_ s: String) -> Int { 3      var right = 1 4      var left = 0 5      var i = 0 6      var result = 0 7       8      if s.count > 0 { 9          result = right - left10          let chars = Array(s.utf8)11          12          //Interate in a incremental window 13          while right < chars.count {14              i = left15                 while i < right {16                     //Check if a duplicate is found17                     if chars[i] == chars[right] {18                         left = i + 119                         break20                     } 21                 i = i + 122              }23          result = max(result,right-left+1)     24          right = right + 125      }26      }27      return result28      }29 }

28ms

 1 class Solution { 2  func lengthOfLongestSubstring(_ s: String) -> Int { 3         if s.characters.count == 0 { 4             return 0 5         } 6          7         let chars = Array(s.utf8) 8         var left = 0 9         var right = 110         var result = right - left11         var i = 012         13         while right < chars.count {14             i = left15             while i < right {16                 if chars[i] == chars[right] {17                     left = i + 118                     break19                 }20                 i += 121             }22             result = max(result,right - left + 1)23             right += 124         }25         26         return result27     }28  }

36ms

 1 class Solution { 2     func lengthOfLongestSubstring(_ s: String) -> Int { 3         var arr = [Int](repeating: -1,count: 256) 4         var s = Array(s) 5         var currentLength = 0 6         var maxLength = 0 7         for i in 0..<s.count { 8             let cValue = Int(s[i].unicodeScalars.first!.value) 9             let preIndex = arr[cValue]10             if arr[cValue] == -1 || i - preIndex > currentLength {11                 currentLength += 112             } else {13                 maxLength = max(currentLength,maxLength)14                 currentLength = i - preIndex15             }16             arr[cValue] = i17         }18         19         maxLength = max(currentLength,maxLength)20         return maxLength21     }22 }

44ms

 1 class Solution { 2     func lengthOfLongestSubstring(_ s: String) -> Int { 3          4         var last:[Int] = Array.init(repeating: -1,count: 127) 5         var start: Int = 0 // 起始位置 6         var maxLength: Int = 0  // 最大长度 7          8         let chars: [Int8]? = s.cString(using: String.EnCoding.utf8) 9         10         for i in 0..<s.count {11             12             let hash_i: Int = Int(chars![i])13             let hash_null: Int = 014             15             if (last[hash_i - hash_null] >= start) {16                 maxLength = max(maxLength,i-start)17                 start = last[hash_i - hash_null] + 118             }19             last[hash_i - hash_null] = i20         }21         maxLength = max(maxLength,s.count - start)22         return maxLength23     }24 }

 

52ms

 1 class Solution { 2     func lengthOfLongestSubstring(_ s: String) -> Int { 3         let chararr = Array(s) 4         let len = s.count 5         var ans = 0 6         var index = Array.init(repeating: 0,count: 128) 7         var j = 0 8         for i in 0..<len { 9             let char = chararr[i]10             if let v = char.unicodeScalars.first?.value {11                 j = max(index[Int(v)],j)12                 ans = max(ans,i - j + 1)13                 index[Int(v)] = i + 114             }15         }16         return ans17     }18 }

84ms

 1 class Solution { 2     func lengthOfLongestSubstring(_ s: String) -> Int { 3         let cs = s.cString(using: .utf8) 4         guard var chars = cs else { return 0 } 5         guard chars.count > 1 else { 6             return 0 7         } 8         chars.removeLast() 9         var maxCount: Int = 010         var i = 0,j = 011         var map: [Int8: Int] = [:]12         while j < chars.count {13             if map.keys.contains(chars[j]) {14                 i = max(map[chars[j]] ?? 0,i)15             }16             maxCount = max(maxCount,j - i + 1)17             map[chars[j]] = j + 118             j += 119         }20         return maxCount21     }22 }

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