Find anagrams (leetcode-438)

lt-438.go

import (
	"crypto/sha1"
	"fmt"
)

func findAnagrams(sentence string, pattern string) []int {
	var arrayIndex []int
	if len(pattern) == 0 || len(sentence) == 0 {
		return arrayIndex
	}
	patternArray := createLookUpTable(pattern)
	patternHash := getHashOfArray(patternArray)
	for i := 0; i <= len(sentence)-len(pattern); i++ {
		subStr := sentence[i:(i + len(pattern))]
		subStrLookUp := createLookUpTable(subStr)
		subStrHash := getHashOfArray(subStrLookUp)
		if subStrHash == patternHash {
			arrayIndex = append(arrayIndex, i)
		}
	}
	return arrayIndex
}

func createLookUpTable(inputString string) [256]byte {
	lookUpArray := [256]byte{}
	for _, v := range inputString {
		lookUpArray[v] = lookUpArray[v] + 1
	}
	return lookUpArray
}

func getHashOfArray(inputArray [256]byte) string {
	patternHash := sha1.New()
	patternHash.Write(inputArray[:])
	return fmt.Sprintf("%x", patternHash.Sum(nil))
}