Given two numbers n and r, the task is to find the value of nPr. nPr represents n permutation r which is calculated as n!/(n-k)!. Permutation refers to the process of arranging all the members of a given set to form a sequence. The number of permutations on a set of n elements is given by n! where “!” represents factorial.
Time Complexity: O(N), where N is the given number. Auxiliary Space: O(N), for recursive stack space while calculating factorial.
Optimization for multiple queries of nPr If there are multiple queries for nPr, we may precompute factorial values and use the same for every call. This would avoid the computation of the same factorial values again and again.
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