06 Apr 2020 | Leetcode 30-Day Challenge: Day 6

Group Anagrams

Difficulty: Medium

Problem statement:

Given an array of strings, group anagrams together.


Input: [“eat”, “tea”, “tan”, “ate”, “nat”, “bat”], Output: [ [“ate”,”eat”,”tea”], [“nat”,”tan”], [“bat”] ] Note:

All inputs will be in lowercase. The order of your output does not matter.

I looked at today’s problem and thought to myself “heh, that’s cute”. Well…I had forgotten one important detail. In java this might have been a cute little exercise - but I wasn’t using java. Oh no, I had decided to use Go - a language in which I knew nothing about.

Fortunately, I was able to solve this entirely without cheating. However, it took at least an hour of research and repeatedly googling “how to do X golang”.

All said and done, my solution initally was too slow to pass the last “performance” test case. I sped it up by removing some redundant logic in the last funciton.

func groupAnagrams(strs []string) [][]string {
    anagramList := [][]string{}
    firstList := []string{ strs[0] }
    anagramList = append(anagramList, firstList)
    for i:= 1; i < len(strs); i++ {
        anagramList = checkAnagramListForMatch(anagramList, strs[i])
    return anagramList

func checkAnagramListForMatch(anagramList [][]string, v string) [][]string {
    for i := range anagramList {
        word := anagramList[i][0]
        if isAnagram(word, v) {
            anagramList[i] = append(anagramList[i], v)
            return anagramList
    anagramList = append(anagramList, []string { string(v) })
    return anagramList

func isAnagram(word string, word2 string) bool {
    if len(word) != len(word2) {
        return false
    for _,v := range word2 {
        word = strings.Replace(word, string(v), "", 1)
    return len(word) == 0