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day06.go
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day06.go
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package day06
import "github.com/alecthomas/participle/v2"
type Leaderboard struct {
Times []int `parser:"'Time' ':' @Int+"`
Distances []int `parser:"'Distance' ':' @Int+"`
}
func NewParser() *participle.Parser[Leaderboard] {
return participle.MustBuild[Leaderboard]()
}
func solve(time int, distance int) (result int) {
for t := 0; t <= time; t++ {
d := t * (time - t)
if d > distance {
result++
}
}
return
}
func (leaderboard *Leaderboard) Part1() int {
result := 1
for i := range leaderboard.Times {
result *= solve(leaderboard.Times[i], leaderboard.Distances[i])
}
return result
}
func smallestPow10GreaterThan(n int) int {
result := 1
for result <= n {
result *= 10
}
return result
}
func concatInts(nums ...int) (result int) {
for _, num := range nums {
result = smallestPow10GreaterThan(num)*result + num
}
return
}
func (leaderboard *Leaderboard) Part2() int {
return solve(
concatInts(leaderboard.Times...),
concatInts(leaderboard.Distances...),
)
}