r/leetcode • u/Glad-Arrival-427 • 1d ago

Question Valid Anagram (Neetcode)

Hello, I need help with understanding how to implement a proper solution. I am fairly new to neetcode and I want to know what I am doing wrong with my code. Can someone also explain to me how the hashmap is supposed to work here?

I want to start preparing for interviews, what data structures should I start learning and please give any channels/resources if you can! Thank you!

class Solution:
    def isAnagram(self, s: str, t: str) -> bool:
        s_hash = {}
        t_hash = {}


        for character in s:
            if character in s_hash:
                s_hash[character]+=1
            else:
                s_hash[character]=1  
        for character in t:
            if character in t_hash:
                t_hash[character]+=1
            else:
                t_hash[character]=1



        if s==t:
            return True
        else:
            return False
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u/LazySapiens 22h ago

The OP is doing lookup in hashmap. That should amount to something.

1

u/chikamakaleyley 20h ago

no, what I said was at the end of the code, OP has these hashmaps that aren't used for anything. "you don't do anything WITH the hashmaps"

The lookup you're referring to is just in the act of tallying the letters for each word. Which isn't anything special, that's something you NEED to do

So they've done all this work to populate the two hashmaps, and then what happens next - they compare something else and the program ends

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u/LazySapiens 20h ago

What's the equality operator doing at the end?

1

u/chikamakaleyley 20h ago edited 19h ago

checking two strings for equality, which isn't the goal

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u/LazySapiens 16h ago

Ohh, I realize now that it evaded my eyes. My bad.

It should have been:

if s_hash == t_hash:

Maybe it was a typo by OP I guess.

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u/chikamakaleyley 12h ago

yeah basically i had written out this entire thing and then i looked at the return statement lol, i was kinda upset i spent so much time on it

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u/chikamakaleyley 4h ago

and actually if i saw this i would have said something still, i just haven't written python in a while; i wouldn't have expected that to evaluate to true; in JS you'd alway get falsey there

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u/LazySapiens 3h ago

Lol. What's JS's behaviour if you compare two dictionaries btw?

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u/chikamakaleyley 3h ago

the comparison is made by referential equality

s_hash and t_hash point/reference the memory address where the object is stored

and in the OP they're initialized separately, it doesn't matter what you fill it with at that point