Tessellate S.T.E.M.S. (2019) - Computer Science - School - Set 3 - Objective Problem 4

The number of functions f : { 1 , 2 , , n } { 1 , 2 , , n } f:\{1,2,\ldots, n\}\rightarrow \{1,2,\ldots,n\} such that f ( x ) x f(x)\neq x are:


This problem is a part of Tessellate S.T.E.M.S (2019)

n n n^n n ! n! ( n 1 ) n (n-1)^n n n 1 n^n-1 n n 1 n^{n-1}

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1 solution

Parth Sankhe
Nov 13, 2018

Each element is the domain will have a choice to become anything in the co-domain through the function, except itself. Therefore each of the n n elements in the domain will have n 1 n-1 choices. Thus the answer = ( n 1 ) n (n-1)^n

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