From 3c078ace91312248c13e273fb9d37bd5825170a0 Mon Sep 17 00:00:00 2001
From: alexchao26 <alexchaoo@gmail.com>
Date: Sat, 26 Dec 2020 18:31:34 -0500
Subject: [PATCH] 2015-day14: reindeers running & stopping

---
 2015/day14/main.go      | 89 +++++++++++++++++++++++++++++++++++++++++
 2015/day14/main_test.go | 26 ++++++++++++
 2 files changed, 115 insertions(+)
 create mode 100644 2015/day14/main.go
 create mode 100644 2015/day14/main_test.go

diff --git a/2015/day14/main.go b/2015/day14/main.go
new file mode 100644
index 0000000..120e23e
--- /dev/null
+++ b/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
+}
diff --git a/2015/day14/main_test.go b/2015/day14/main_test.go
new file mode 100644
index 0000000..f5c4019
--- /dev/null
+++ b/2015/day14/main_test.go
@@ -0,0 +1,26 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func Test_reindeerOlympics(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		part  int
+		want  int
+	}{
+		{"part1 actual", util.ReadFile("input.txt"), 1, 2660},
+		{"part2 actual", util.ReadFile("input.txt"), 2, 1256},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := reindeerOlympics(tt.input, tt.part); got != tt.want {
+				t.Errorf("reindeerOlympics() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}