Permutation problem

#1

sir i am practicing a question of permutation but i am not able to understand the implementation of the question. please tell me how can i solve this question. and how to write code for it.
question link–> https://www.hackerearth.com/practice/math/number-theory/basic-number-theory-1/practice-problems/algorithm/permutation-again/

#2

hello @tejuschaturvedi0

editorial of the question is already given. please read it.
after that u just need one if else statement to implement it.



    if(n==1):
        print('1')

   else  if n%2!=0:
       print((n*n-3)//2)
    else:
       print((n*n-2)//2)
#3

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