Boustrophedon transform: Difference between revisions

=={{header|Wren}}==

{{libheader|Wren-math}}

Just the basic task for now.

<syntaxhighlight lang="ecmascript">import "./math" for Int

var boustrophedon = Fn.new { |a|

var k = a.count

var cache = List.filled(k, null)

for (i in 0...k) cache[i] = List.filled(k, 0)

var b = List.filled(k, 0)

b[0] = a[0]

var T

T = Fn.new { |k, n|

if (n == 0) return a[k]

if (cache[k][n] > 0) return cache[k][n]

return cache[k][n] = T.call(k, n-1) + T.call(k-1, k-n)

}

for (n in 1...k) b[n] = T.call(n, n)

return b

}

System.print("1 followed by 0's:")

var a = [1] + ([0] * 14)

System.print(boustrophedon.call(a))

System.print("\nAll 1's:")

a = [1] * 15

System.print(boustrophedon.call(a))

System.print("\nAlternating 1, -1")

a = [1, -1] * 7 + [1]

System.print(boustrophedon.call(a))

System.print("\nPrimes:")

a = Int.primeSieve(200)[0..14]

System.print(boustrophedon.call(a))

System.print("\nFibonacci numbers:")

a[0] = 1 // start from fib(1)

a[1] = 1

for (i in 2..14) a[i] = a[i-1] + a[i-2]

System.print(boustrophedon.call(a))

System.print("\nFactorials:")

a[0] = 1

for (i in 1..14) a[i] = a[i-1] * i

System.print(boustrophedon.call(a))</syntaxhighlight>

{{out}}

<pre>

1 followed by 0's:

[1, 1, 1, 2, 5, 16, 61, 272, 1385, 7936, 50521, 353792, 2702765, 22368256, 199360981]

All 1's:

[1, 2, 4, 9, 24, 77, 294, 1309, 6664, 38177, 243034, 1701909, 13001604, 107601977, 959021574]

Alternating 1, -1

[1, 0, 0, 1, 0, 5, 10, 61, 280, 1665, 10470, 73621, 561660, 4650425, 41441530]

Primes:

[2, 5, 13, 35, 103, 345, 1325, 5911, 30067, 172237, 1096319, 7677155, 58648421, 485377457, 4326008691]

Fibonacci numbers:

[1, 2, 5, 14, 42, 144, 563, 2526, 12877, 73778, 469616, 3288428, 25121097, 207902202, 1852961189]

Factorials:

[1, 2, 5, 17, 73, 381, 2347, 16701, 134993, 1222873, 12279251, 135425553, 1627809401, 21183890469, 296773827547]

</pre>