Ugly numbers efficient program solution explained | 2 Methods

This lecture explains what are ugly numbers and how to solve ugly numbers using brute-force method as well as dynamic programming method. Both the codes are given in the link below.
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[kishalaybhattacharya]

your approach with the multiplication table is wrong, try to upload videos with right concept, otherwise it'll be confusing for others

[anoopm]

Your multiplication solution is not exactly correct. For example, 2*7 is not an ugly number. Your DP solution is correct though.The basic concept is any ugly number multiplied with 2, 3 or 5 will give an ugly number.As we only keep ugly numbers in the dp array, we will get the answer

[praveenchouhan]

i think this approach deviates at a point wherein the 11th ugly number comes 2*7=14 which is incorrect, the dp solution is a thing after that but i think something is wrong in the main approach!!!

[charankumar]

Actually 1 is also a power of those, 2 power 0 is 1, 3 power 0 is 1, 5 power 0 is 1 at(1:03)

[nocredits]

I don't understand the way we uptade the next number ugly number (nm2= ugly[i2] * 2). I mean, why does it work?

[be_like__prateek]

Your multiplication solution is not exactly correct. For example, 2*7 is not an ugly number.

[prateekaryan]

Thank you for the explanation Bhaiya :)
But your intuitive solution is misleading. In your intuitive solution, you are basically taking a minimum number from tables of 2, 3 and 5 at each iteration, by this approach, we will even have 14, 21.... and so on as an ugly number which is incorrect.
Though, final dp approach is correct.

[animeblastford]

Guys, this approach is wrong. Using a multiplication table means that at some point you will insert 14(2*7) or 21(3*7) and so on, which are not ugly numbers.

[sudheer-suri]

out of thin air you thought you should use 2, 3, 5 tables ? you should've explained what made you use that method instead of just explaining the code in English.

[RahulKumar-wfxx]

Great videos, Really Helpful keep up the great work !!

[jubba]

Hello, i need to write a programto find the 1500th ugly number, without any input. (C++) Could you help me out?

[therawbean]

Your method will give 14 as the ugly number, which is not. Please correct the error

[himanshu]

It's wrong this time because it will give 14 also as ugly number but it is not!! Delete the video bro!!

[micromir]

everyone is jumping straight to 2, 3, 5 tables to explain the solution. How did you arrive at the table?

[pradeep]

Don't post wrong logic and waste our time

[saravanan]

how to write a recursive formula for this problem? because generally for all the dp problems I have been seeing some recursive formula, why not in this problem?

[ajayjangid]

solution should be explained as per exact "dp"-approach's intitution.

[anonymoussloth]

This approach is wrong. 7x2 = 14 This is not an ugly number

[sonuranjansingh]

sare tutorial padh ke video banane aa jate hai bhai concept kaha hai

[midhileshmomidi]

How is brute force method tc is nlogn anyone pls explain