func Solve32() (solution int) {
perms := util.LexicographicsPermutations([]int{1, 2, 3, 4, 5, 6, 7, 8, 9})
prods := make(map[int]struct{})
for p := range perms {
oneFourFour := p[0] * (p[1]*1000 + p[2]*100 + p[3]*10 + p[4])
if oneFourFour < 10000 {
prod := p[5]*1000 + p[6]*100 + p[7]*10 + p[8]
if oneFourFour == prod {
prods[prod] = struct{}{}
}
}
twoThreeFour := (p[0]*10 + p[1]) * (p[2]*100 + p[3]*10 + p[4])
if twoThreeFour > 1000 && twoThreeFour < 10000 {
prod := p[5]*1000 + p[6]*100 + p[7]*10 + p[8]
if twoThreeFour == prod {
prods[prod] = struct{}{}
}
}
}
for p, _ := range prods {
solution += p
}
return
}
func Solve24() (solution int) {
p := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
// This could be done faster doing in-place permutations on a single slice
i := 0
for p := range util.LexicographicsPermutations(p) {
if i == 999999 {
for _, n := range p {
solution *= 10
solution += n
}
return solution
}
i++
}
return
}