Number of Ways to Divide a Long Corridor - Leetcode 2147 - Python

[@jonaskhanwald566]

Was going through the editorial for 1 hour and got headache, this 20 mins explanation relieved me from the pain

[@joydeeprony89]

What an explanation , You are a savior to this interview preparation universe.

[@CS_n00b]

please keep up these daily challenge solutions!

[@the_witcherr275]

Very Helpful, Thanks Navdeep😉

[@1vader]

More efficient version of the combinatorial solution: MOD = 10**9 + 7 class Solution: def numberOfWays(self, corridor: str) -> int: total = 1 seats = 0 divider_spots = 1 for c in corridor: if seats == 2: if c == "P": divider_spots += 1 else: total = (total * divider_spots) % MOD divider_spots = 1 seats = 1 elif c == "S": seats += 1 if seats != 2: return 0 return total

[@jasonswift7468]

Hi NeetCode. Members need domain driven design instructional videos. Thank you.

[@haoranliu517]

would be better if you can upload more videos for your pro members. Did not see Java solutions posted on your website. Great explanation. 😄

[@yousrimeftah5768]

am so sad i didn't came up with a solution ,the problem looked too easy after this combinatorics solution Thank You .

[@m.kamalali]

If we do bottom up for recursive solution space can be optimized to o(1) " no need combinatorics"!

[@OP-yw3ws]

Thanks. I was so frustrated caz of this problem

[@dattagangji7634]

Be regular bro. I love your content!

[@王瀚君-c3j]

Great explanation!

[@pastori2672]

they definitely made this problem "Hard" because of the description

[@Pegasus02Kr]

I think I'm good with solution 1. 2 is confusing.

[@orchlonchinbat2214]

Thank you. :)

[@arihantbedagkar7678]

Space Optimization to O(1): previous_seat_index = seats = 0 count = 1 for index, char in enumerate(corridor): if char == 'S': seats += 1 if seats > 2 and seats & 1: count = (count * (index - previous_seat_index)) % (10 ** 9 + 7) previous_seat_index = index return count if seats and not seats & 1 else 0

[@NeetCodeIO]

Beautiful!!

[@toriamfoobar]

I don't really catch the use of Mod... Could you explain why we need it please?

[@rajsuriyang3427]

I added them got the wrong answer. I guess i should multiply them.

[@ethanphelps5308]

yeah, the number of ways to place dividers between one pair is completely independent from the number of ways to place dividers between other pairs so the product rule applies for counting all possible orientations

[@riyaz3409]