leetcode-go/leetcode/medium/3.go

package main

func lengthOfLongestSubstring(s string) int {
	max := 0
	for i := 0; i < len(s); i++ {
		// a map stores all runes showed up after index i
		m := map[byte]int{s[i]: 1}
		for j := i + 1; j < len(s); j++ {
			if m[s[j]] == 1 {
				max = maxInt(len(m), max)
				break
			}
			m[s[j]] = 1
		}
		max = maxInt(len(m), max)
	}
	return max
}