Pandigital prime: Difference between revisions
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{{libheader|Wren-math}}
{{libheader|Wren-fmt}}
===Using digits 1 to n===
This makes use of the optimization in the Factor entry.
<lang ecmascript>import "/math" for Int
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The largest pandigital decimal prime which uses all the digits 1..n once is:
7,652,413
</pre>
===Using digits 0 to n===
Applying the Factor logic for the digits 0..n, we only need to check 8, 5 and 3 digit cases as it can't be any of the others.
<lang ecmascript>import "/math" for Int
import "/fmt" for Fmt
// generates all permutations in lexicographical order
var permutations = Fn.new { |input|
var perms = [input]
var a = input.toList
var n = a.count - 1
for (c in 1...Int.factorial(n+1)) {
var i = n - 1
var j = n
while (a[i] > a[i+1]) i = i - 1
while (a[j] < a[i]) j = j - 1
var t = a[i]
a[i] = a[j]
a[j] = t
j = n
i = i + 1
while (i < j) {
t = a[i]
a[i] = a[j]
a[j] = t
i = i + 1
j = j - 1
}
perms.add(a.toList)
}
return perms
}
System.print("The largest pandigital decimal prime which uses all the digits 0..n once is:")
for (n in [7, 4, 2]) {
var perms = permutations.call((0..n).toList)
for (i in perms.count - 1..0) {
if (perms[i][0] == "0" || perms[i][-1] % 2 == 0 || perms[i][-1] == 5) continue
var p = Num.fromString(perms[i].join())
if (Int.isPrime(p)) {
Fmt.print("$,d", p)
return
}
}
}</lang>
{{out}}
<pre>
The largest pandigital decimal prime which uses all the digits 0..n once is:
76,540,231
</pre>
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