Practical numbers: Difference between revisions
Added Go
(→{{header|Wren}}: Slightly simpler.) |
(Added Go) |
||
Line 157:
=={{header|Delphi}}==
See [https://rosettacode.org/wiki/Practical_numbers#Pascal Pascal].
=={{header|Go}}==
{{trans|Wren}}
{{libheader|Go-rcu}}
<lang go>package main
import (
"fmt"
"rcu"
)
func powerset(set []int) [][]int {
if len(set) == 0 {
return [][]int{{}}
}
head := set[0]
tail := set[1:]
p1 := powerset(tail)
var p2 [][]int
for _, s := range powerset(tail) {
h := []int{head}
h = append(h, s...)
p2 = append(p2, h)
}
return append(p1, p2...)
}
func isPractical(n int) bool {
if n == 1 {
return true
}
divs := rcu.ProperDivisors(n)
subsets := powerset(divs)
found := make([]bool, n) // all false by default
count := 0
for _, subset := range subsets {
sum := rcu.SumInts(subset)
if sum > 0 && sum < n && !found[sum] {
found[sum] = true
count++
if count == n-1 {
return true
}
}
}
return false
}
func main() {
fmt.Println("In the range 1..333, there are:")
var practical []int
for i := 1; i <= 333; i++ {
if isPractical(i) {
practical = append(practical, i)
}
}
fmt.Println(" ", len(practical), "practical numbers")
fmt.Println(" The first ten are", practical[0:10])
fmt.Println(" The final ten are", practical[len(practical)-10:])
fmt.Println("\n666 is practical:", isPractical(666))
}</lang>
{{out}}
<pre>
In the range 1..333, there are:
77 practical numbers
The first ten are [1 2 4 6 8 12 16 18 20 24]
The final ten are [288 294 300 304 306 308 312 320 324 330]
666 is practical: true
</pre>
=={{header|J}}==
| |||