Partition function P: Difference between revisions

</pre>

=={{header|Wren}}==

{{trans|Julia}}

{{libheader|Wren-big}}

Although it may not look like it, this is actually a decent time for Wren which is interpreted and the above module is written entirely in Wren itself.

<lang ecmascript>import "/big" for BigInt

var p = []

var pd = []

var partDiffDiff = Fn.new { |n| (n&1 == 1) ? (n + 1)/2 : n + 1 }

var partDiff = Fn.new { |n|

if (n < 2) return 1

pd[n] = pd[n-1] + partDiffDiff.call(n-1)

return pd[n]

}

var partitionsP = Fn.new { |n|

if (n < 2) return

var psum = BigInt.zero

for (i in 1..n) {

var pdi = partDiff.call(i)

if (pdi > n) break

var sign = (i-1)%4 < 2 ? 1 : -1

psum = psum + p[n-pdi] * sign

}

p[n] = psum

}

var start = System.clock

var N = 6666

p = List.filled(N+1, null)

pd = List.filled(N+1, 0)

p[0] = BigInt.one

p[1] = BigInt.one

pd[0] = 1

pd[1] = 1

for (n in 2..N) partitionsP.call(n)

System.print("p[%(N)] = %(p[N])")

System.print("Took %(System.clock - start) seconds")</lang>

{{out}}

<pre>

p[6666] = 193655306161707661080005073394486091998480950338405932486880600467114423441282418165863

Took 1.428762 seconds