Saved from https://leetcode-cn.com/problems/first-unique-character-in-a-string/submissions/

firstUniqChar.go

func firstUniqChar(s string) int {
    var cnt [26]int
    for _, c := range s {
        cnt[c-'a']++
    }
    for i, c := range s {
        if cnt[c-'a'] == 1 {
            return i
        }
    }
    return -1
}