advent-of-code/tools.go
2023-12-08 19:09:00 -07:00

59 lines
955 B
Go

package aoc
import (
"bufio"
"fmt"
"os"
)
func Runner[R any, F func(*bufio.Scanner) (R, error)](run F) (R, error) {
if len(os.Args) != 2 {
fmt.Fprintln(os.Stderr, "Usage:", os.Args[0] , "FILE")
}
input, err := os.Open(os.Args[1])
if err != nil {
fmt.Fprintln(os.Stderr, err)
}
scan := bufio.NewScanner(input)
return run(scan)
}
func Reverse[T any](arr []T) []T {
for i := 0; i < len(arr)/2; i++ {
arr[i], arr[len(arr)-i-1] = arr[len(arr)-i-1], arr[i]
}
return arr
}
// greatest common divisor (GCD) via Euclidean algorithm
func GCD(a, b uint64) uint64 {
for b != 0 {
t := b
b = a % b
a = t
}
return a
}
// find Least Common Multiple (LCM) via GCD
func LCM(integers ...uint64) uint64 {
if len(integers) == 0 {
return 0
}
if len(integers) == 1 {
return integers[0]
}
a, b := integers[0], integers[1]
result := a * b / GCD(a, b)
for _, c := range integers[2:] {
result = LCM(result, c)
}
return result
}