Search found 1 match
- Thu Oct 07, 2021 12:36 am
- Forum: National Math Olympiad (BdMO)
- Topic: BdMO National Higher Secondary 2020 P8
- Replies: 8
- Views: 9211
Re: BdMO National Higher Secondary 2020 P8
Let $S \rightarrow \{1,2,3,...,n\}, f(n) = $ the number of total permutations satisfying the given condition and $g(x)$ = the number of total possible permutations demoting a number $x \in S$. We can demote a number $x$ to $x-1$ different positions or swap $x$ with $\{1,2,3,...,x-1\}$ and we can't c...