Group Anagrams (LeetCode 49) | Full solution with 2 methods and examples | Study Algorithms

You are given an array of strings, you need to group the anagrams. Two strings are said to be anagrams if they have the exact same characters with the same frequency. The placement can change though. Watch this video to learn 2 methods to solve this problem. We will take advantage of properties of anagrams and use it in our favor. At the end we will see a dry-run of the code to see what is actually happening behind the scenes.

00:00 - Intro
01:12 - Problem statement and description
04:40 - Method 1: Categorize by Sorting
09:03 - Method 2: Categorize by Frequency
13:09 - Dry-run of Code
15:44 - Generate Frequency String
18:09 - Final Thoughts

📚 Links to topics I talk about in the video:

📖 Reference Books:

My Recording Gear:

💻 Get Social 💻

#leetcode #programming #interview

[dhavalchaudhary]

I generally not hit like on youtube videos, but this guy nailed it. Thanks for your community contribution NIkhil.

[devprakash]

loved your explanation . But 1 thing I would like to correct . The time complexity of method 1 will be O(n k log k ), where k is the length of the string, n is total strings . This is because sorting a string would take (k log k ) . Any way awesome explanation . thanks

[WhosShamouz]

I was missing ONE idea and it popped in my head when I saw your first method, amazing explanation!

[amitbhattacharya]

I got really surprised by so a vivid and clear explanation. I appreciate your efforts.

[vikashsharma]

sir you explaination to any algorithm is the best explanation i had ever seen ...only your explanation is enough to solve the problem no need to see the code

[plutomessi]

Dhanyavad bhaiya, you are the best teacher I have seen on youtube😭

[ricardohernandezmendez]

At the beginning it was difficult to find out how to solve this problem, but with this explanation it make it easy to solve it. Thank.

[ElinaAdibi-bt]

Thank you, you explained it very well!

[akshanshsharma]

In the sorting way, the time complexity is not O(nlogk) but rather O(n.klogk)

[Donkle]

Hey, I found this video trough the article and thank you for all the work, it really helped me. The solution of method 2 at line 34 has a mistake: "freq++;", you can't ++ an array, so we need to do freq[c - 'a']++ :)

[mazthespaz]

i'm new to python and this was my solution

def smash(str):

tmp = 1
orda = ord('A')-1
ls = len(str)

for i in range( ls ):
tmp = tmp * (ord(str[i]) - orda)

return tmp


def groop(wordlist):

grope = {}

for word in wordlist:
hashy = smash(word)
if hashy not in grope:
grope[hashy] = []

grope[hashy].append(word)

return [val for val in grope.values()]

if __name__ == '__main__':
# arr = [ 'cat', 'tea', 'tan', 'ate', 'nat', 'bat' ]
arr = [ 'eat', 'cars', 'tea', 'scar', 'a', 'listen', 'silent']

print (groop(arr))

[edd_gos]

bro, thank you for the video. it was very usefull (like all your videos) <3

[shaileshsathe]

Very well explained the techniques, code and dry-run. Great work Nikhil.

[lofiboy]

We need to write getfrequency string string method also sep?

[RohitSharma-qjp]

great video and best ever explaination ever

[shahbazhussain]

If I use sorting logic will be my solution wrong?
I am facing difficulty in understanding the HasMap and Frequency Concept.

[ramsidh]

great explanation with animation step by step

[hersheynohara]

That's an amazing explanation! 👏👏

[jst]

8:14 should be "nat", not sorted string "ant".
Otherwise your tutorials are the best regarding leetcode problems, because you explain with examples what should the code do.

[yfchina]

this there any better way for a frequency string algothrim?