Derangements Small
Hard
Computer Mathematics
Combinatorics
33 views
Problem Statement
Compute number of derangements for n
Input Format
One integer n.
Output Format
One integer.
Example
4
9
Constraints
0
Input / Output Format
Input Format
One integer n.
Output Format
One integer.
Constraints
0
Examples
Input:
4
Output:
9
Example Solution (Public)
Use recurrence D(0)=1,D(1)=0,D(n)=(n-1)*(D(n-1)+D(n-2)).
Official Solution Code
Use recurrence D(0)=1,D(1)=0,D(n)=(n-1)*(D(n-1)+D(n-2)).
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