func familySize(sieve *euler.Sieve, base, part int) (size int) {
orig := euler.DigitsOf(base)
work := make([]int, len(orig))
size = 0
found := false
for _, d := range orig {
if d == part {
found = true
break
}
}
if !found {
return
}
for value := part; value <= 9; value++ {
copy(work, orig)
for i := range orig {
if work[i] == part {
work[i] = value
}
}
prime := euler.OfDigits(work)
if sieve.IsPrime(prime) {
size++
}
}
return
}
// Compute all of the digit permutations of the number.
func allPermutations(base int) (perms []int) {
perms = make([]int, 1)
perms[0] = base
work := euler.DigitsOf(base)
iwork := sort.IntSlice(work)
for !euler.NextPermutation(iwork) {
perms = append(perms, euler.OfDigits(work))
}
return
}