Cycle detection: Difference between revisions
Added Wren
(Added Wren) |
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Line 2,509:
Cycle length = 6
Start index = 2</pre>
=={{header|Wren}}==
Working from the code in the Wikipedia article:
<lang ecmascript>var brent = Fn.new { |f, x0|
var lam = 1
var power = 1
var tortoise = x0
var hare = f.call(x0)
while (tortoise != hare) {
if (power == lam) {
tortoise = hare
power = power * 2
lam = 0
}
hare = f.call(hare)
lam = lam + 1
}
tortoise = hare = x0
for (i in 0...lam) hare = f.call(hare)
var mu = 0
while (tortoise != hare) {
tortoise = f.call(tortoise)
hare = f.call(hare)
mu = mu + 1
}
return [lam, mu]
}
var f = Fn.new { |x| (x*x + 1) % 255 }
var x0 = 3
var x = x0
var seq = List.filled(21, 0) // limit to first 21 terms say
for (i in 0..20) {
seq[i] = x
x = f.call(x)
}
var res = brent.call(f, x0)
var lam = res[0]
var mu = res[1]
System.print("Sequence = %(seq)")
System.print("Cycle length = %(lam)")
System.print("Start index = %(mu)")
System.print("Cycle = %(seq[mu...mu+lam])")</lang>
{{out}}
<pre>
Sequence = [3, 10, 101, 2, 5, 26, 167, 95, 101, 2, 5, 26, 167, 95, 101, 2, 5, 26, 167, 95, 101]
Cycle length = 6
Start index = 2
Cycle = [101, 2, 5, 26, 167, 95]
</pre>
=={{header|zkl}}==
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