Recursion - Permutations (Theory + Code + Tips)

This is part 2 of the subset + string recursion series. Here we cover some important tips to permutation problems with #recursion.

Take part in the learning in public initiative! Share your learnings on LinkedIn and Twitter with #DSAwithKunal & don't forget to tag us!

👉 Resources

=========================================
Timestamps:
00:00 Introduction
00:22 What is Permutation?
01:53 Permutation using Recursion
11:48 Code for Permutation
15:42 Returning output as an ArrayList
20:12 Counting Number of Permutations
24:35 Outro

#placement #dsa #interviews

[subhankarkanrar]

It you don't understand in first watch, don't skip it. See it again, you will understand. In my case i was not able to understand in my first watch, when i repeat, i got the whole thing clear

[PRASHANTKUMAR-ilob]

9:30 If anyone have the confusion with brackets, kunal mistakenly used Inclusive in place of exclusive bracket and vice versa.

[muenidorcas]

The best recursion video ever! I have been watching all your recursion videos and I can now solve recursion challenges. Looking forward to more of these. Thank you for demystifying the monster!

[nooruskhan]

bhai top class :), gazab padhaye ho, recusrsion khud se sochna aagya, Thanks alot

[MiddleClassBoy-lbyi]

Logic becomes more clear after watching it again

[yogpooja-vqpp]

Your content is amazing, I went through lots of DSA courses on youtube, but no video develops the understanding and solution approaching mindset as you do. Blessed that I found you.🔥🔥🔥

[_PoojaDahifale]

thanks kunal before watching your i have a lots of doubts related to permutation ... after watching video ... all doubt are cleared.

[manwinsingh]

I did permutations just by seeing the previous video. Power of Kunal and recursive tree🔥🔥🔥🔥

[mayanksingh]

Thumbnail clears that the topic which we are going to see in recursion (recurring photos) LOL
Great work Kunal you're helping us in many ways. 😊

[Cloud-]

it wouldn't hurt to leave a like. It is the least we can do for Kunal.

[prakharsinha]

it is no way wrong if i say your lectures are really mesmerizing....just amazing Kunal #NailediT🔥

[hargunsingh]

Hi Kunal,

Your recursion playlist on YouTube has been a game-changer for me! I have learned so much and have been able to apply the concepts in my coding projects. I would love to see a new lecture series on dynamic programming. I know it's a challenging topic, but I trust your teaching style and explanations to make it more approachable. Keep up the great work!

[akaay]

People in comments are all geniuses. (excluding me)
Most of them understood this at once.

I personally had to rewatch is many times and draw the recursion tree on notebook few times to understand it.

Great video Kunal.
Recursion is like that unless u do on paper few timess u dont understand.

[Moch]

You're helping me with backtracking so much. THANK YOU!!!

[adityapalve]

Been following the videos daily and keeping up with them. This is very fun ngl. Great work.

[sadmansakibmugdho]

Hello Kunal. I want to know, After the DSA course, will you show us how to use our skills in open source and all that stuffs till how to approach in a company? If not then please consider this.🙏🙏🙏

[amruthaa]

Thank you so much!!! <3 I FINALLY UNDERSTOOD RECURSION.

[siddhigupta]

plss make more videos your way of teaching is just fab...

[dark_techyy]

Kunal, here is O(n) solution for permutation count -

int pc( str )
{
if ( str is empty ) return 0;
if( str.length() == 1) return 1;
int original_len = str.length();
int rem_len = pc( str.substring(1) );

return ( original_len * rem_len );
}

I am building my thought process ... thanks!!! ❤️❤️✔️

[navrosesinghjohal]

simpler better code for permutation: static void permutations(String p, String up){
if(up.isEmpty()){
System.out.println(p);
return;
}
int n = up.length();
for(int i =0;i<n;i++){
char ch = up.charAt(i);
permutations(p+ch, up.substring(0, i) + up.substring(i + 1));
}
}