package main

import "fmt"

func main() {
	fmt.Println(lengthOfLongestSubstring(" "))
}

func lengthOfLongestSubstring(s string) int {
	if len(s) == 0 {
		fmt.Println("直接")
		return 0
	}
	if len(s) == 1 {
		return 1
	}
	left, right := 0, 1
	window := 1
	result := 0
	hash := make(map[rune]struct{}, 0)
	hash[rune(s[0])] = struct{}{}
	for right < len(s) {
		if _, ok := hash[rune(s[right])]; ok {
			window--
			delete(hash, rune(s[left]))
			left++

		} else {
			hash[rune(s[right])] = struct{}{}
			right++
			window++
			result = max(result, window)
		}

	}
	return result
}