Subarrays Sums Divisible by K (Leetcode 974) Algorithm Explained

NADOS also enables doubt support, career opportunities and contests besides free of charge content for learning. In this video, we discuss the problem count subarrays with sum divisible by K using hashmaps in java. In this problem,

1. You are given an array of integers(arr) and a number K.
2. You have to find the count of subarrays whose sum is divisible by K.

#hashmaps #datastructure #algorithms

[champ]

The negative mod trick is main part to identify in this problem.. Thanks for explaining that 👍🏼

[prateekkatiyar]

Sir you are a legend. You make everything look so easy.

[hemaladani]

Hello @pepcoding, can you please explain Leetcode 523? Its using HashMap but there is no good explaination.

[Manish-wwlg]

your repititive explanation is so amazing sir😍😍
make things learned while watching the video🤩🤩🤩

[nishanttiwari]

You missed a case of if(rem==0) then also count++ becuse its the sum staring from first index and need to be checked seperately

[sandeepgampa]

Awesome 👍. Your explanation looks so good that I can code directly without any second thought. Thanks a lot bro 👏👍

[aisakyunhotahai]

I am very happy that I have discovered this channel, but sad also why not earlier, Anyways now i think my placements prep is going to be OP :)

[VikasGupta-oklh]

Best possible explaination for this sum

[yapping_yash]

a lotttt better than any other solutions on YT

[aratibhandare]

What a simplified and well explained solution

[prathameshpawar]

#include <bits/stdc++.h>
int subArrayCount(vector<int> &arr, int k) {
map<int, int> mpp;
mpp[0]=1;
int count=0, presum=0, rem=0;
for(int i=0;i<arr.size();i++)
{
presum+=arr[i];
rem = ((presum%k)+k)%k;
count+=mpp[rem];
mpp[rem]+=1;
}
return count;
// Write your code here.
}
is this right in
c++?

[lambarahul]

why did you added 0, 1 in the hashmap initially? Can you please explain that?

[KAUSHALDOKANIA]

Just 1 min into the video, liked the way you are explaining. LIKED the video.

[sahilhemnani]

I just can not thank this guy enough :)

[gautamtyagi]

line no. 9. -> should be map.put(0, -1) instead of map.put(0, 1) isn't it? please confirm. thanks.

[JGyanRaj]

Subscribed it... Pahla video dekhne par hi subscribe kar liye... Bhai kitne patience ke sath padhate ho... Its just awesome/amazing...More power to u brother.

[directhit]

It would be better if you could explain how you came to conclusion that the remainders should be equal .

[Elon-musk-]

Mazza aagya Waah kaafi time ke baad 2 videos dekhi hai ek saath !!!! Keep going

[paragroy]

Nice video keep on making such videos.

[abc-ymzs]

good explanation sir if possible try to provide c++ solution