Update 3. Longest Substring Without Repeating Characters.go

[JessonChan]

improve

[yangwenmai]

please add some improve benchmark result?

[halfrost]

Both your commit and original solution time complexity is O(n). I guess these improve means the code is shorter, beacause it doesn't call max() function. @JessonChan

[JessonChan]

@halfrost max function will be inlined to function lengthOfLongestSubstring, so it's the same.
@yangwenmai this pr will reduce loops https://play.golang.org/p/q0M3r1KZbp6

[halfrost]

Thanks, wonderful! Your judgment conditions are more excellent. I learned a lot. @JessonChan