2015-day14: reindeers running & stopping

2015/day14/main.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strings"
+
+	"github.com/alexchao26/advent-of-code-go/mathutil"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func main() {
+	var part int
+	flag.IntVar(&part, "part", 1, "part 1 or 2")
+	flag.Parse()
+	fmt.Println("Running part", part)
+
+	ans := reindeerOlympics(util.ReadFile("./input.txt"), part)
+	fmt.Println("Output:", ans)
+}
+
+func reindeerOlympics(input string, part int) int {
+	reindeerToDistanceMap := map[string][]int{}
+
+	for _, line := range strings.Split(input, "\n") {
+		var name string
+		var speed, runTime, restTime int
+		_, err := fmt.Sscanf(line, "%s can fly %d km/s for %d seconds, but then must rest for %d seconds.", &name, &speed, &runTime, &restTime)
+		if err != nil {
+			panic(err)
+		}
+
+		// 1-index the distances slice, indices line up with elapsed time
+		reindeerToDistanceMap[name] = append(reindeerToDistanceMap[name], 0)
+
+		var dist int
+		remainingRunTime := runTime
+		remainingRestTime := restTime
+		for t := 0; t < 2503; t++ {
+			if remainingRunTime > 0 {
+				dist += speed
+				remainingRunTime--
+			} else {
+				remainingRestTime--
+				if remainingRestTime == 0 {
+					remainingRunTime = runTime
+					remainingRestTime = restTime
+				}
+			}
+			reindeerToDistanceMap[name] = append(reindeerToDistanceMap[name], dist)
+		}
+	}
+
+	// for part 1 return the furthest end distance (time 2503 seconds)
+	if part == 1 {
+		var furthest int
+		for _, distSli := range reindeerToDistanceMap {
+			furthest = mathutil.MaxInt(distSli[2503], furthest)
+		}
+		return furthest
+	}
+
+	// for part 2, score each second, then find the highest score
+	reindeerScores := map[string]int{}
+	for sec := 1; sec <= 2503; sec++ {
+		var names []string
+		var bestDist int
+		for name, distanceSli := range reindeerToDistanceMap {
+			if distanceSli[sec] > bestDist {
+				names = []string{name}
+				bestDist = distanceSli[sec]
+			} else if distanceSli[sec] == bestDist {
+				names = append(names, name)
+			}
+		}
+
+		for _, name := range names {
+			reindeerScores[name]++
+		}
+	}
+
+	var bestScore int
+	for _, v := range reindeerScores {
+		bestScore = mathutil.MaxInt(bestScore, v)
+	}
+
+	return bestScore
+}