Is it only me or the brute force was difficult to understand?

correction: 21:18 time complexity should be O(logN)* . Great explanation though

Correction, @striver, at 2:45 the answer for arr=[5,7,10,12] and k=6 is 8 and not 7. Thanks for these series

No doubt you explain nicely, everything gets crystal clear after going through your lecture video, but I wonder how do you come up with this type of solution on your own. It's like scientist making some mind boggling discoveries.

Understood! Super fantastic explanation as always, thank you so so much for your effort!!

I have never seen anything fantastic than this , I already enrolled in paid DSA course but trust me guys if I found out this channel and dsa sheet before that i have never taken the paid dsa course this is just awesome

Happy to solve without watching solution , took 4hrs to figure out approach and code it . Yeah happy me🙂

Thank you for the explanation. Two edge cases that should improve running time: if (k < vec[low]) return k; if (k > vec[high] - n) return k + n;

you are far better than any of the comedians and so called celebrities . Thanks!

Optimal one is just out of the box kind of thing ❤

Awesome explanation man, after some self dry run of few examples, I completely got the concept. Thanks!

Very beautiful explained. With logic

brute force assume you have an empty array and we have some k value, say k = 4the missing number, so in this case the missing value would be 4 Case 1:- where the value at a index in the array < k now just consider the empty array again and we added a number smaller than k to it, say 2, so now when we again try to find the 4th missing number we would get it as 5 ( as 1 3 4 5 , as 2 already present in the array, hence the missing value shifts by one position ahead and 5 is the 4th missing value), hence whenever we get a number in the array smaller than k, the kth missing value shifts by position ahead Case2 :- where value at a index in array > k now consider empty array again and we added a number greater than k, assume k = 4 and we added 7 to it, here the kth missing element will be 4 itself, as even though seven was added - it indicated that the array might or might not contain the first 6 numbers and as the k = 4 value is lesser than 7, so this kth value would also come under missing value, and as 7 > k, so no effect on k occur. So k is the missing element

understood Thank you striver for such an amazing explanation

🤯 didn't thought for the binary search approach

Crazy derivation sir! thank youu for the series

Pure Genius Explanation....

Great explanation !

Bhaiya you are doing a great work ❤

For [4,7,9] and k = 3, answer will be simple that is 3, bcz k < arr[0] for all these cases we can directly return k. And at the end we can use arr[high] like:- " int diff = (arr[high] - high + 1); int miss = k - diff; return arr[high] + miss; "

great explanation for low+k.

This guy's just incredibleee!

Loved the explanation.

how beautifully u explained the brute force. top level intuition👑.

thankfully I was able to do it by my own. I was able to think this approach myself

The subtlety in the algorithm is not considering (arr[mid] - (mid+1) == k) coz if we hit that we have no way to figure out the answer(take k=1 as example and your arr[mid]-(mid+1) matches with k, that is why there is no condition for equals k. Idea is to move high to the index where the missing numbers are lesser than k, that way we get the low end and all we got to do is add the remaining. would have been good if this point was insisted coz if you forget the algorithm and try to write from scratch thinking oh it's binary search, you're gonna get stuck in an interview.

simple problem koo completed or comopleted problem koo simple, bana koi aap sai sikhai, you are master of dsa🤩🤩🤩🤩❤❤❤❤❤❤❤❤

Understood Very Well!

Thanks a lot Bhaiya . Crystal Clear

nicely explained bro ....thanks

Literally, I spent one day trying to solve the brute force but when I saw the brute force in the video I was shocked how is it possible?😐😐

Brilliant. Thanks!

@takeUforward maybe you can update the time complexity in description for binary search as O(log2N)

For brute force in the array 5,7,10,12 k=6. For 5 -> k=7, 7 -> k=8, 10 exceeds the value hence k becomes 8 and 8 should be returned. Hope this helps!

amazing solution , maja agya

Understood Bhaiya ..!!

awesome explanation

bar bar dekho... hazaar bar dekho or practice kro is the key here

letsss goooo!! Understood

Fantastic. Thank you.

you are the best brother

i knew there was better algo than quick select thanks

Nice explanation Sir ❤❤❤

Totally dependent on you bro ❤

Understood, thank you.

Understood Sir.

good question .. maza aya karke

I coudln't think this way !! best solution

Helped a lot 🙂🙂😌

Best explanation

when are you planning to complete this series ?

Understood✅🔥🔥

Awesome Sir......

understood 😇

21:23 error time complexity will be o(log base 2 n) that is o(log n)

Legendary Boss

Understooooooood!

the brute force solution is beautiful.\

after a good brainstorming session it's time to see the video :)

thank you so much sir

understood!

Thank you so much!! this is one of the trickiest binary search problem which I was able to figure out on my own. class Solution { public int findKthPositive(int[] arr, int k) { if(k < arr[0]) { return k; } int low = 0; int high = arr.length-1; while(low

why this question is tagged easy on leetcode

how in explanation high

Understood ❤

Understood !! 😎😎

Hey Bhagwan , The BS intuition great

Thank you Bhaiya

An easier brute force code:- int missingK(vector < int > vec, int n, int k) { // Write your code here. int i=0,j=1,missing=0; while(missing!=k){ if(vec[i]!=j){ missing++; j++; } else{ i++, j++; } } j--; //We did this because j moved 1 forward because of the if statement. So to get our answer, we need to move j backward by 1. return j; }

Bhaiya the GfG link to the question in a2z DSA Sheet the question is bit different to what explained in video for example in the test case n = 3 , k=1 {32 , 59 ,77} the first missing number is 33

Understood!!

After Watching 3 time I Finally understand

Both the solutions are difficult to grasp at first go. It needs another revisit for sure

I just wonder this is only first video bit difficult to understand both brute force and optimal.

******** ONE OBSERVATION ********* what if the number of missing elements = k , i.e. int missing = arr[mid]-(mid+1); missing == k can we write this: if(missing

understoood :)

understood

at 21:17 , time complexity would be O(logn) [ just a human error]

Understood🙃

can someone explain me the missing number formulae in the brute force as its setting correct for the case which striver has taken but once I am changing the values in the array and trying to find the new missing number I am not getting what I should get, did I get the question in a wrong manner , am I missing any key point of the question ?

Understand 🎉

the optimal solution definitely does not fit in the easy category striver 😂 btw amazing lecture🙏🏻♥

Understood

what if the input arr[]=[2] and k=1 ? According to this logic i think answer is 2 but actully it is 1....

at 19:45 sir have taken value of "more" as arr[high]-high-1 but should it be arr[high]-high+1?.....can anyone plz explain??

this question scared the living daylights out of me, couldn't solve it even brute force was this really an easy question

Understood :)

why cant we use arr[mid] -- (mid + 1 ) formula to calculate the missing number instead of the formula arr[high ] -- (high + 1) ??

intuition behind incrementing k is not clear, are we assuming kth element is k inititally and why incrementing k leads to answer, i understood the code but intuition is not clear

just one question though, we are finding missing via arr[mid]-mid+1; why are we using using arr[high] ?? like fore expression arr[high]-high+1 ?? arr[high]+more ??

Bro by when your whole dsa sheet will be covered, placement coming up?any eta approx?

For brute force this case 2,5,6,7,9 and k=5 will fail.. correct me..

GodLike!

your brute force solution is optimal solution for me 🤣🤣

woozy of a question

Why does it not work on gfg?

where are notes as i m unable to find it in description?

bhaiya bs ques tha ki : jaise aap figure out krrh ho ki 1,2,3,4 ideally 4,7,9,10 arr m hone chaiye the. so inko substract kre to missing number milenge. iska logic nhi bnra dry run krte wkt. mtlab wo missing number maths se aara h but kaise aaya ye nhi feel ara..

13:10 opposite polarity

bhaiya iska link mein galat question ka code hai aur sheet mein link bhi nahi hai