day5, part2. making map efficient

day5/dayFive.go

@@ -2,6 +2,7 @@ package day5
 
 import (
 	"fmt"
+	"log"
 	"math"
 	"os"
 	"strconv"
@@ -15,7 +16,26 @@ type Almanach struct {
 	WaterToLight,
 	LightToTemp,
 	TempToHum,
-	HumToLocation map[int]int
+	HumToLocation EfficientMap
+}
+
+type Triplet struct {
+	target, source, rangeLen int
+}
+type EfficientMap struct {
+	mappings []Triplet
+}
+
+func (m EfficientMap) applyMap(source int) int {
+	for _, triplet := range m.mappings {
+		sourceStart, sourceEnd := triplet.source, triplet.source + triplet.rangeLen
+		if source >= sourceStart && source <= sourceEnd {
+			diff := source - sourceStart
+			return triplet.target + diff
+		}
+	}
+
+	return source
 }
 
 func applyMap(source int, mapping map[int]int) int {
@@ -28,25 +48,32 @@ func applyMap(source int, mapping map[int]int) int {
 }
 
 func (a Almanach)locationForSeed(seed int) int {
-	soil := applyMap(seed, a.SeedToSoil)
-	fert := applyMap(soil, a.SoilToFert)
-	water := applyMap(fert, a.FertToWater)
-	light := applyMap(water, a.WaterToLight)
-	temp := applyMap(light, a.LightToTemp)
-	hum := applyMap(temp, a.TempToHum)
-	location := applyMap(hum, a.HumToLocation)
+	log.Print("starting calc of location for seed %d", seed)
+	soil := a.SeedToSoil.applyMap(seed)
+	fert := a.SoilToFert.applyMap(soil)
+	water := a.FertToWater.applyMap(fert)
+	light := a.WaterToLight.applyMap(water)
+	temp := a.LightToTemp.applyMap(light)
+	hum := a.TempToHum.applyMap(temp)
+	location := a.HumToLocation.applyMap(hum)
 	return location
 }
 
 func Run() int {
 	fmt.Println("the day 5")
-	inputDir := "day5/example"
+	inputDir := "day5/input"
 	seedToSoil := fmt.Sprint(inputDir, "/seed-to-soil")
+	log.Print("finished seed map")
 	soilToFert := fmt.Sprint(inputDir, "/soil-to-fertilizer")
+	log.Print("finished soil map")
 	fertToWater := fmt.Sprint(inputDir, "/fertilizer-to-water")
+	log.Print("finished fert map")
 	waterToLight := fmt.Sprint(inputDir, "/water-to-light")
+	log.Print("finished water map")
 	lightToTemp := fmt.Sprint(inputDir, "/light-to-temperature")
+	log.Print("finished light map")
 	tempToHum := fmt.Sprint(inputDir, "/temperature-to-humidity")
+	log.Print("finished temp map")
 	humToLocation := fmt.Sprint(inputDir, "/humidity-to-location")
 
 	seedsFileName := fmt.Sprint(inputDir, "/seeds")
@@ -63,6 +90,7 @@ func Run() int {
 		}
 		seeds = append(seeds, seed)
 	}
+	log.Print("finished for seeds file", seeds)
 
 	almanach := Almanach{
 		SeedToSoil: ReadMap(seedToSoil),
@@ -73,9 +101,12 @@ func Run() int {
 		TempToHum: ReadMap(tempToHum),
 		HumToLocation: ReadMap(humToLocation),
 	}
+	log.Print("created almanach")
 
 	result := math.MaxInt
+	log.Print("before seed range")
 	for _, seed := range seeds {
+		log.Printf("checking for seed %d", seed)
 		location := almanach.locationForSeed(seed)
 		if location < result {
 			result = location
@@ -85,8 +116,9 @@ func Run() int {
 	return result
 }
 
-func ReadMap(filename string) map[int]int {
-	result := make(map[int]int)
+func ReadMap(filename string) EfficientMap {
+	log.Printf("reading in map from %s", filename)
+	result := make([]Triplet, 0)
 	bytes, err := os.ReadFile(filename)
 	if err != nil {
 		panic(fmt.Sprintf("error reading file %s", filename))
@@ -104,10 +136,8 @@ func ReadMap(filename string) map[int]int {
 		if err1 != nil || err2 != nil || err3 != nil {
 			panic(fmt.Sprint("error converting one of the numbers: ", nums))
 		}
-		for i := 0; i < rangeLength; i++ {
-			result[sourceStart+i] = destinaitonStart + i
-		}
+		result = append(result, Triplet{destinaitonStart, sourceStart, rangeLength})
 	}
 
-	return result
+	return EfficientMap{result}
 }