97 lines
2.1 KiB
Go
97 lines
2.1 KiB
Go
package main
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import (
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"fmt"
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// "strings"
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"bufio"
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// "math"
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"os"
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"strconv"
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"regexp"
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"sync"
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)
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type Race struct {
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mu sync.Mutex
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total int
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}
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func (r *Race) WeRaceBoys(time, distance int, wg *sync.WaitGroup) {
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// As we just need to find the minimum necessary and then subtract it from
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// the maximum, probably a good idea starting form the middle
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tempTime := 0
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for i := int(time/2); i > 0; i-- {
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tempDist := i * (time - i)
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if tempDist <= distance {
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tempTime = i + 1
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break
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}
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}
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// If the minimum is tempTime, then the maximum is time - tempTime
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// time - 2*tempTime is the number of possible victories
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r.mu.Lock()
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r.total *= (time - (2 * tempTime - 1))
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r.mu.Unlock()
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wg.Done()
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}
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func check(e error) {
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if e != nil {
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panic(e)
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}
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}
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func PrintAndWait(x ...any) {
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fmt.Print(x...)
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fmt.Scanln()
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}
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func main() {
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file, err := os.Open("./inputs/day06_input")
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check(err)
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defer file.Close()
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r := Race{
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total: 1,
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}
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var wg sync.WaitGroup
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_ = wg
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// Regex that finds the numbers in a row
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renum := regexp.MustCompile("[0-9]+")
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_ = renum
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scanner := bufio.NewScanner(file)
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time, distance := make([]int, 0), make([]int, 0)
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tempStrings := make([]string, 0)
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// Generic, would work for more rows
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for scanner.Scan() {
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tempStrings = append(tempStrings, scanner.Text())
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}
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// Now populate time and distance
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timeStr := renum.FindAllString(tempStrings[0], - 1)
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distStr := renum.FindAllString(tempStrings[1], - 1)
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// Both should be the same length
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for i := range timeStr {
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num, _ := strconv.Atoi(timeStr[i])
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time = append(time, num)
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num, _ = strconv.Atoi(distStr[i])
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distance = append(distance, num)
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}
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// E.g.: if I hold the button for 1ms and then release it, it will travel at
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// 1mm/ms fo the remaining amount of seconds.
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// We can skip the holding down 0 and tMAX ms.
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// Once we find the MIN amount of ms necessary to win, the limit is
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// MAX - MIN
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for i := 0; i < len(time); i++ {
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wg.Add(1)
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go r.WeRaceBoys(time[i], distance[i], &wg)
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}
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wg.Wait()
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PrintAndWait(r.total)
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}
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