Pandigital prime: Difference between revisions
Added Go
(→Algol 68: Common code: Fix even number detection) |
(Added Go) |
||
Line 213:
The largest pandigital decimal prime is:
7652413
</pre>
=={{header|Go}}==
{{trans|Wren}}
{{libheader|Go-rcu}}
<lang go>package main
import (
"fmt"
"rcu"
)
// only small factorials needed
func factorial(n int) int {
fact := 1
for i := 2; i <= n; i++ {
fact *= i
}
return fact
}
// generates all permutations in lexicographical order
func permutations(input []int) [][]int {
perms := [][]int{input}
a := make([]int, len(input))
copy(a, input)
var n = len(input) - 1
for c := 1; c < factorial(n+1); c++ {
i := n - 1
j := n
for a[i] > a[i+1] {
i--
}
for a[j] < a[i] {
j--
}
a[i], a[j] = a[j], a[i]
j = n
i += 1
for i < j {
a[i], a[j] = a[j], a[i]
i++
j--
}
b := make([]int, len(input))
copy(b, a)
perms = append(perms, b)
}
return perms
}
func main() {
outer:
for _, start := range []int{1, 0} {
fmt.Printf("The largest pandigital decimal prime which uses all the digits %d..n once is:\n", start)
for _, n := range []int{7, 4} {
m := n + 1 - start
list := make([]int, m)
for i := 0; i < m; i++ {
list[i] = i + start
}
perms := permutations(list)
for i := len(perms) - 1; i >= 0; i-- {
le := len(perms[i])
if perms[i][le-1]%2 == 0 || perms[i][le-1] == 5 || (start == 0 && perms[i][0] == 0) {
continue
}
p := 0
pow := 1
for j := le - 1; j >= 0; j-- {
p += perms[i][j] * pow
pow *= 10
}
if rcu.IsPrime(p) {
fmt.Println(rcu.Commatize(p) + "\n")
continue outer
}
}
}
}
}</lang>
{{out}}
<pre>
The largest pandigital decimal prime which uses all the digits 1..n once is:
7,652,413
The largest pandigital decimal prime which uses all the digits 0..n once is:
76,540,231
</pre>
| |||