The 90th percentile delivery promise
A grocery delivery app in Singapore promises customers a delivery window. The operations team does not use the average, because a few very late orders hide behind it. They quote a percentile of the delivery times instead, and everyone must compute it the same way.
Task: line 1 holds the delivery times in minutes (integers separated by spaces, at least one value). Line 2 holds an integer p from 0 to 100. Sort the values ascending (x[0] is the smallest) and use linear interpolation: let pos = (n - 1) * p / 100, lo = floor(pos), frac = pos - lo. The answer is x[lo] + (x[lo + 1] - x[lo]) * frac; when lo is the last index the answer is simply x[lo]. Print the answer with exactly 2 decimals.
Sample tests
Input
30 25 41 22 60 35 28 52 31 45 90
Expected output
52.80
Input
12 18 25 40 50
Expected output
21.50
Your answer is also checked against 4 hidden tests.
Need a hint?
Work out the fractional position first, then split it into a whole index and a leftover fraction.
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