This is the problem statement. Here is the editorial. I understood the editorialist solution. But I want to solve this problem using Combinatorics(using Permutations and Combinations). Any help will be highly appreciated. Thank You.
I'm curious, why did you want a solution with combinations rather than DP in the first place? (I think it was fun, so no complaints here, just wondering what motivated that.)
I actually used to be really good maths and specifically P&C and was really creative when I was 16/17. Now my brain just don't work and I can't think anything creative when solving harder problems. I knew there is solution based on combinatorics so I wanted to know how can I come up with its solution.
Sure, the combinatorial solution is
(both are equivalent, just whichever summation is easier to read/understand)
Here's the implementation I submitted (and got AC):
Can you please your solution. Thank You
I'm curious, why did you want a solution with combinations rather than DP in the first place? (I think it was fun, so no complaints here, just wondering what motivated that.)
I actually used to be really good maths and specifically P&C and was really creative when I was 16/17. Now my brain just don't work and I can't think anything creative when solving harder problems. I knew there is solution based on combinatorics so I wanted to know how can I come up with its solution.
Ah, I see. How old are you now that (as you say) "your creativity has left you"?
I'm 22.
I'm excited to see you gain it back!