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SRM 730 DIV2 MEDIUM

The expectation of discrete random variable is given by Σ(Pi*Xi)

Where Xi = Value of random variable
Pi = Probability of random variable

Let us suppose that if we choose ith element as the minimum element, then we have to choose remaining x-1 element out of remaining elements which are greater than i.

Number of ways to do this is: C(n-i, x-1)
The total number of ways to select x elements out of n is C(n,x).
Thus the probability of event is C(n-i, x-1) / C(n,x).

If it is not possible to select x-1 elements out of remaining elements, then the probability is 0.

Check out the implementation:

Happy Coding :)

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