35 lines
743 B
Nim
35 lines
743 B
Nim
import random, math, strformat
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randomize()
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const
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maxN = 20
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times = 1_000_000
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proc factorial(n: int): float =
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result = 1
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for i in 1 .. n:
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result *= i.float
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proc expected(n: int): float =
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for i in 1 .. n:
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result += factorial(n) / pow(n.float, i.float) / factorial(n - i)
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proc test(n, times: int): int =
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for i in 1 .. times:
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var
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x = 1
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bits = 0
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while (bits and x) == 0:
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inc result
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bits = bits or x
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x = 1 shl rand(n - 1)
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echo " n\tavg\texp.\tdiff"
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echo "-------------------------------"
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for n in 1 .. maxN:
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let cnt = test(n, times)
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let avg = cnt.float / times
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let theory = expected(n)
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let diff = (avg / theory - 1) * 100
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echo fmt"{n:2} {avg:8.4f} {theory:8.4f} {diff:6.3f}%"
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