Question:

Method: A Map is used to record the character and index, and if the next character is present in the Map, the recount is started, so that the maximum string length can be obtained in one loop.

class LongestSubstringWithoutRepeatingCharacters { fun lengthOfLongestSubstring(s: String): Int { if (s.length < 2) { return s.length } var maxLength = 1 val map = mutableMapOf<Char, Int>() map[s[0]] = 0 var index = 1 while (index <= s.lastIndex) { val ch = s[index] if (map.containsKey(ch)) { map[ch]? .let { index = it + 1 map.clear() } continue } map[ch] = index if (map.size > maxLength) { maxLength = map.size } index++ } return maxLength } } fun main() { val input = "dvdf" val longestSubstringWithoutRepeatingCharacters = LongestSubstringWithoutRepeatingCharacters() print(longestSubstringWithoutRepeatingCharacters.lengthOfLongestSubstring(input)) }Copy the code

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