Lecture37: Recursion - Subsets / Subsequences of String [Theory + Code] 

Bhaiya you teach things in such a manner that they don't seems difficult at all. Respect++

After understanding the technique and logic of the 1st problem I solved the 2nd problem myself without even watching your logic and solution. Thanks for giving me the confidence, Sir. Hope you get well soon. Like you, I am also sick right now and pushing hard towards recovery but I made sure to watch your videos and practice coding myself😊

Thanks Bhaiya for consistency of this 10 days recursion serial for deduction Attendance marked 💯💯

In this and in the DP series, the examples chosen and the sequence in which they have been taught is very logical hence it helps build the concept and the ideas very well. Kudos!

aapp jaldi se thikk ho jao bhaiya ☺️ ❤️ me to Blindly trust ke sath aapki video dekhta hoo. everyday jaldi se video dekh kar next video ke liye ready rahta hoooo😃 you give us consistency & made us consistent. dill se shukriya ❤️

Me (after watching every promotional parts) : jab aapki dukaan pe free me Shahi Paneer mil raha ho to paisa deke maggie khane koun jaae... 😅😅😅 Thank you bhaiya....💯💯💯💯🌸🌺🌻🌹🌷🌼💐 Itna achha course banane ke liye.. Get very well soon..

Phli baar mei samajh nahi aya tha bhaiya, but second time dekha and khud se notebook mei dry run jab kiya toh maja hi agaya solve krke, dusri wali toh khud se hi hogayi! Thank you so much!

Bhaiya, apka Josh high rakho. Ham log apke videos regularly dekhte hain. Aap hi hamka sahara ho. U r doing great!!! Also, backlog khatam kar raha hu. Din ke 2 videos dekh hi leta hu....

Amazing visualization of the problem helped me to understand and appreciate the problem solving, many thanks Babar!

Loved this video alot!! Marked my attendance! Commenting for Better Reach! The Best DSA course ever on youtube!🔥🔥🔥🔥🔥

By Include/Exclude logic we cannot solve the case when there are duplicates in input. We need a backtracking logic here

Bhaiya semesters chal rhe h iski wjh se 10 11 video backlog chal rhi h But you are consistent Thankyou bhaiya

bhaiya maza aagaya saare questions ban gaye ab maza aaraha hai ab shayad kuch hojae thankyou so much bhaiya >>>>>

love u bhai ,Respect from heart....U r teaching us with lot of energy and dedication even when u r infected with corona salute u ...bhai..RESPECT++

Final year project ke liye kuch series bana do

At first i didn't get the concept at all but after watching this video again after a day now i feel confident and learn this new concept of backtracking.

vector subsets(vector& nums) { vector ans; int n = nums.size(); for(int i = 0;i

thank you bhaiya aapne humare liye itna accha content create kar rhe ho , woh bhi absolutely free mein. Thank you bhaiya💌🤟

if we are not popping out at any time. how are we getting the subsets? The subset problem code will create vector output of redundant values. Leetcode also not catched it. I request leetcode to check it again.

Thank you bhaiyya for everything you are doing great work all concepts are clear till this video pray for fast recovery

Thanks bhaiya, apki waja se ye backtracking samaja aaya, ye bohot dino se samjne ka kosis kar raha tha lekin nhi aaya, sirf apki ye ek video ke waja se aaya, thanks bhaiya

Samajh me aa gaye dono questions bhaiya...

Your teaching skill is awesome ❤❤

#include using namespace std; void solve(vector& nums,int index,vector output,vector& ans){ int length=nums.size(); //base case if(index>=length){ ans.push_back(output); return; } //exclude solve(nums,index+1,output,ans); //include int element=nums[index]; output.push_back(element); solve(nums,index+1,output,ans); } int main(){ vector nums={1,2,3}; int index=0; vector output; vector ans; solve(nums,index,output,ans); cout

Truly the best explanation for these problems. No one on youtube has explained it in such an easy way. Bhaiya you are the best

Finally a series worth the time.

iss question ko samjhne ke liye maine apne ek ghante idhar udhar kharab kiye aur yahan 2 question 27 min me samjh aa gye.thank you so much bhaiya

really so easy question because of you, i taught this concepts of various teacher but cant understood how it's work but today, my all doubts is so clear thankyou Babbar bhaiya love you so much

Definitely This is, 🌠 THE BEST DSA SERIES 🌠 Thank you so much bhaiya 🙏

Thank you for this wonderful 10day recursion Awesome series 👏 👌

bhaiya nhi aaye samaj

dono question aa gaye samjh mein Bhaiya.Thanks❤

Subset has 2 to power n elements and subsequence is (2 to power n) - 1 i.e 2^n - 1 because we exclude empty subset from it

bhaiya dono question samaj mein aa gaye

Best content to understand Recursion in simple way amazing . Very helpful

Dono samjhe aa gye. abb homework karna hai. Thank you for this course. learning a lot

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thanks for all videos best dsa videos

hats off to your consistency.... marked present🤩🤩

// power set --> bitn manipulation se bhi hosaktahai! class Solution { private: bool CB(int i, int j){ return((i)&(1

the way you explain the recursion tree is excellent!!🥰🥰🥰

Bhaiyya dono samjh me aa gaye consistency++ Attendance++

for(int =1;i>=0;i++) { cout

Bhai aap ke explain karne ka tarika ek dam badia ha Both questions are clear Your course is awesome

Loved this video alot!! Marked my attendance! Commenting for Better Reach!

Question Subsets :- Time: O(pow(2,n)) Space: O(n*pow(2,n))

very helpful video bhaiya

Bhaiya dry run kar diya karo pls, usse bahot jyada clarity milti hai aur approach jyada din tak yaad bhi rehta hai, average studnts ki need hai voh, usse spoon feeding mat consider karo please.

THE BEST DSA COURSE

Why am I always afraid of facing these kind of problems ?? so sad, this problem is too hard to derive the logic, he didn't even say how can we take the observation from output?

1.Subsets for java. class Solution { public void call_subset(int[] nums,List ans,List first,int index) { if(index>=nums.length) { ans.add(first); return ; } List copyForInclude = new ArrayList(first); List copyForExclude = new ArrayList(first); //exclude call_subset(nums,ans,copyForExclude,index+1); //include int element=nums[index]; copyForInclude.add(element); call_subset(nums,ans,copyForInclude,index+1); } public List subsets(int[] nums) { List ans= new ArrayList();; List output= new ArrayList();; int index=0; call_subset(nums,ans,output,index); return ans; } } 2.Subsequences of String import java.util.ArrayList; class Solution { public static void subsequences_fun(String str,ArrayList ans,String output,int index) { if(index>=str.length()) { if(output.length()>0) ans.add(output); return ; } subsequences_fun(str,ans,output,index+1); char ele=str.charAt(index); output+=ele; subsequences_fun(str,ans,output,index+1); } public static ArrayList subsequences(String str) { // Write your code here ArrayList ans=new ArrayList(); String output=""; int index=0; subsequences_fun(str,ans,output,index); return ans; } }

apki ye wali T-shirt mughe bahut acchi lagi .... video bhi .. maza aagya bhaiya thankyou

Best Dsa series Bhaiya plz take care of your health Get well soon

Bhaiya...kya hee bolun...you have taught me this in a very fine way...😍thanks

Thanks bro...i was stuck on these type of problems from many days

Bhaiya dono questions bahut achchhe se samajh me aa gaye...

How's the Josh? ... Very high bhaiya.... aise hi content laate rehne... humare saath saath corona bhi ... apka baat mann jayga... Hoping for a soon recovery... #WeLoveBabbar

Hello bhaiya, I am watching this series but lagging with lectures. So don't think that we are not watching ❤️

PRESENT SIR ... RI8 NOW AT LECT -36 REACH ++ CONCEPT ++

//home problem solution 1 #include using namespace std; vectorsolve(string s) { vectorans; long long a=pow(2,s.length()); for(int i=0;i>1; } ans.push_back(output); } return ans; } int main(){ string s; cin>>s; vectorans; ans=solve(s); for(string x:ans) cout

Best way of learning recursion ❤️❤️

subsets using Iterative approch vector subsets(vector& nums) { vector ans; // vector output; int i = 0; // solve(nums , ans , output , i); vector output = {}; ans.push_back(output); while(i < nums.size()){ int size = ans.size(); for(int j = 0 ; j < size ; j++){ output = ans[j]; output.push_back(nums[i]); ans.push_back(output); } i++; } return ans; }

Watching ur videos regularly daily...But currently I am 10-12 lectures behind... I was busy with my end sems.

outstanding! Understood every bit of it!

I am having one doubt in question 1... don't we need to pop_back element from output vector while backtracking?

Dono question bhaut aache se samaj me aye bhaiya 🥰🥰🙏🙏🙏🙏

Samaj aaya bhaiya.... bhaiya you told you are very good in aptitude.... so plz think about that also bhaiya... because the way you teach it is super understandable....

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before rat in maze problem i was nothing understand.. after coming from that question i able to understand what & how this is working... 😋😋..

Thankyou sir we loved it!!!

Thanku sooo much bhaiya. ❤️❤️❤️ Take care!!!!

Thankyou bhaiya for this amazing lecture❤️🔥🔥

JAVA CODE - SUBSET public static void main(String args[]) { int[] arr = { 1, 2, 3 }; List resList = new ArrayList(); List outputList = new ArrayList(); int index = 0; subsets(arr, resList, outputList, index); } private static void subsets(int[] arr, List resList, List outputList, int i) { if (i >= arr.length){ resList.add(outputList); return; } //exclude subsets(arr, resList, new ArrayList(outputList), i+1); //include outputList.add(arr[i]); subsets(arr, resList, outputList, i+1); }

Incase of Java users, be careful, it wont work without backtracking... public List subsets(int[] nums) { List subsets = new ArrayList(); List subset = new ArrayList(); int index = 0; solve(index,nums,subset,subsets); return subsets; } private void solve(int index, int[] nums, List subset, List subsets) { System.out.println("Index: " + index + " " + subset); if(index >= nums.length){ System.out.println("Index: " + index + " " + subset + " PUSHED"); subsets.add(new ArrayList(subset)); return; } solve(index+1,nums,subset,subsets); subset.add(nums[index]); solve(index+1,nums,subset,subsets); System.out.println("Backtracking!"); subset.remove(subset.size() -1); }

Damn, i used to be hell scared by these questions earlier. Now these look easy. Thanks to you!

You are great...aap jo bhi bolte ho sab samjh aata hai bhaiya😅

yes bhaiya understand both question . attendance marked

thanks bhaiya apka support ka liya,hamarae internal and sem end chalra hai isliya 2 3 lag ma hai magar we are covering up ,thanks alot for the videos

Going strong day by day

haa bhaiya smj aye dono questions..🥰😍

I don't have words to thank you bhai..

Thank you very much. You are a genius.

Both question are clear bhaiya... Great explanation... Thanks for that...

Solution in Java class Solution { public List subsets(int[] nums) { List result = new LinkedList(); List output = new LinkedList(); findSubsets(nums, 0, result, output); return result; } private void findSubsets(int[] nums, int index, List result, List output){ if(index==nums.length){ result.add(new LinkedList(output)); return; } //Include output.add(nums[index]); findSubsets(nums, index+1, result, output); //Exclude output.remove(output.size()-1); findSubsets(nums, index+1, result, output); } }

Present bhaiya! Watching your lecture 21 today.

Bhaiya maja aa gya ++ PS : bhaiya yei bateyi muje ek doubt h aapne subset wale problem m backtracking q ni ki after including the element bcoz Mera backtracking ka vode chal rha h or apka bhi ?

Great and excellent Bhaiya the way u explained . Enjoying to learn..........👌👌💯💯💯💯

Thanks bhaiya, this course is really helpful... 🔥🔥

1st question me, outut bale vector me, only one element, index bala push hona chahiye, phir he 2 elements (1, 2) ek saath kese push ho raha he?

mazza agaya ......

Ab samajh aye ye questions. Finally

Very well explained. Thank you so much.

bhaiya dono questions samajh m aa gaye !

Bhaiya leetcode pe questions to solve ho rhe hai pr optimization nhi ban rhi hai jyadatar TLE hi milta hai

nice way of teaching

uda diya ye lecture bhaiya ne

Now I'm pro in recursion..thank you

thankyou so much bhaiya by the way vector easy hai use karna baki normal array ke case mai thora jada mehanat hai thora sa jada utna bhi nhi bhot easy code tha

bhaiya dono question samjh aagye....reach++

Dono questions samaz aagaye bhaiya