mathtools/internal/lib/mobius.go

49 lines
1.0 KiB
Go

/*
Copyright © 2025 filifa
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package lib
func MobiusSieve(n uint) chan int {
sieve := make([]int, n)
for i := 0; i < int(n); i++ {
sieve[i] = i
}
ch := make(chan int)
go func() {
for i := 0; i < int(n); i++ {
if i == 0 || i == 1 || sieve[i] != i {
ch <- sieve[i]
continue
}
ch <- -1
for j := 2 * i; j < int(n); j += i {
if j%(i*i) == 0 {
sieve[j] = 0
}
sieve[j] /= -i
}
}
close(ch)
}()
return ch
}