aoc2023/day-18/one.go
2023-12-22 21:57:00 +00:00

40 lines
976 B
Go

package main
import (
"math"
"regexp"
)
var r = regexp.MustCompile(`(?P<direction>[A-Z]) (?P<count>[0-9]+) \((?P<colour>.*)\)`)
func fromRegex(imager *imager, lines []string) {
for _, line := range lines {
direction, count := func() (string, int) {
x := getParams(r, line)
return x["direction"], mustConv(x["count"])
}()
imager.add(direction, count)
}
}
func buildImage(withParser func(imager *imager, lines []string), imager *imager, lines []string) {
withParser(imager, lines)
}
// one returns the area of the polygon described by imager.space
func one(lines []string) int {
imager := newImager()
buildImage(fromRegex, imager, lines)
area := 0
for i := 0; i < len(imager.space); i++ {
next := imager.space[(i+1)%len(imager.space)]
area += imager.space[i].X*next.Y - imager.space[i].Y*next.X
}
// add perimeter to area within perimeter
area = len(imager.space) + (int(math.Abs(float64(area))) / 2)
return area - len(imager.space)/2 + 1
}