Regular Expression Matching - Dynamic Programming Top-Down Memoization - Leetcode 10

0:00 - Read the problem
3:55 - Drawing Solution
19:00 - Coding Solution

leetcode 10

#regular #expression #python

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[sudheerk]

I can't thank enough for this video! Even after spending nearly 3 hours on various videos showing direct DP (bottom-up) solution, and countless posts in Discuss section with no clear explanation, I could not understand how the formulae are derived. But.... this is gem of a video and probably the only video on Youtube explaining the Top-Down approach.

In fact, it is better to try Top-Down approach in interviews. Directly trying to attack a problem with DP formula can lead to disasters. If the interviewer is not dumb expecting a specific answer involving DP, he/she/they should be okay with Top-Down+Memoization approach.

Thanks again! Keep making such amazing videos.

[parambole]

If I crack my FB interviews it's only going to be because of this channel. Keep up the "NEET" work :)

[jimwu]

To be honest, I never would have even guessed that this is a Dynamic Programming problem. Once you started explaining the decision tree, it ALL made sense. Thanks for teaching me something new!

[chinmaym]

I really appreciate how clean your code was and was so easy to understand

[dollyvishwakarma]

OMG, the question looked so tough, but you made it soo easy !! Another awesome explanation. Great fan of your NEET coding style :)

[xinchenyi]

The clearest explanation I've seen!!! You are awesome :)

[michaeldunlap]

This is a fabulous and thorough explanation. The decision tree explanation and visual for the asterisk was what did it for me. Thank you!

[autoot]

Great explanation! I really like how you easily added memoization to the brute force algorithm. Other DP solutions were SO complicated. This explanation was perfect.

[arpanbanejee]

Simply mind-blowing explanation, you made it so simple!! Thanks you! Please keep up the good work!

[AbanoubAsaad-YT]

BEST EXPLANATIONS ARE HERE :)
Thank you so much for these quality videos!

[buttercup]

I was struggling a lot with this question. Your video cleared my doubts. Thanks for sharing!

[hakoHiyo]

Great explanation! You explained the algorithm very clearly. I'm not even Python guy, but I still liked your video!

[yukselpolatakbyk]

You make this question easy to udnerstand. Thank you for all your amazing solutions!!

[kanwarkajla]

great explanation the vibe of ur videos is relaxing!

[TheRetrobek]

If someone didn't get the cache part, try printing out the (i, j) pairs with the following example: text="aaabaaa" and pattern = "a*b*a*".
If you take a careful look, since we are backtracking, there are cases where we check the same (i, j) pairs. And that's why caching helps.

[ruizhu]

I really appreciate your explanation, so clean, so logical!

[vdyb]

What a brilliant solution and in-depth explanation for this seriously hard problem !!! WOW .... Thank you !!!!

[santoshr]

Thanks alot for helping me understand the issue, I was doing the bottom up and solution was failing in leetcode on last 2 test cases. After watching this video I understood we need to do bound check on index "i" - stupid of me missing such a basic thing. Now solution worked

[podkxrd]

This explanation makes the whole process clean and simple.

[Iamnoone]

Thanks Hokage for explaining it really well.Seen a lot of videos where people directly start drawing table.Will memoized soln be enough for an interview or do we have to give a bottom up soln too??