Assuming the input string and pattern is in lowercase alphabets, here is the golfing solution

var result []int patternFrequency := [26]int{} charFrequency := [26]int{} for _, c := range pattern { patternFrequency[c-97] += 1 } for i := 0; i < len(pattern); i++ { charFrequency[input[i]-97]++ } if charFrequency == patternFrequency { result = append(result, 0) } for i := 1; i