might be making a mistake starting 2018...

2019/day06/part2/main.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"adventofcode/util"
+	"fmt"
+	"strings"
+)
+
+func main() {
+	input := util.ReadFile("../input.txt")
+
+	// split it into a slice of all strings
+	inputSliced := strings.Split(input, ",")
+
+	// send the input to a helper function that will return a map {planetName string: planetItOrbits string}
+	mapOfOrbits := makeGraphDependencyList(inputSliced)
+
+	sanOrbitsToCom, youOrbitsToCom := recurseToCOM(mapOfOrbits, "SAN"), recurseToCOM(mapOfOrbits, "YOU")
+
+	// need to find where the two run over the same planet...
+	// these two variables will store the indexes within the slices, that corresponds to the same planet
+	var indexOfYouPlanet, indexOfSanPlanet int
+
+	// iterate through the SAN orbits, nest a loop to search for the same planet in the YOU orbits
+	// a map would have better time complexity... due to lookup time
+	for indexSan, sanOrbitPlanetString := range sanOrbitsToCom {
+		// a boolean to track if the planet was found in the you orbit
+		var foundYouPlanet bool
+		// iterate through YOU orbits and if the same planet is found, update the indexYou and foundBool
+		for indexYou, youOrbitPlanetString := range youOrbitsToCom {
+			if youOrbitPlanetString == sanOrbitPlanetString {
+				indexOfYouPlanet, foundYouPlanet = indexYou, true
+				break
+			}
+		}
+
+		// if it was found, set the indexOfSanPlanet and stop the looping
+		if foundYouPlanet {
+			indexOfSanPlanet = indexSan
+			break
+		}
+	}
+
+	// subtract two for the SAN and YOU planets (they're pointers to a planet, not extra orbits to traverse)
+	fmt.Println("result is: ", indexOfYouPlanet+indexOfSanPlanet-2)
+}
+
+func makeGraphDependencyList(inputSlice []string) map[string]string {
+	resultMap := make(map[string]string)
+	for _, v := range inputSlice {
+		slicedPlanets := strings.Split(v, ")")
+		inner, outer := slicedPlanets[0], slicedPlanets[1]
+		// set the key-value pair on the map/"object"
+		resultMap[outer] = inner
+	}
+
+	return resultMap
+}
+
+func recurseToCOM(mapOfOrbits map[string]string, planet string) []string {
+	// added to handle part2
+	planetsToComSlice := make([]string, 0)
+
+	// start the result at one because triggering this function is using the outerPlanet
+	// and needs to include that initial orbit from innerPlanet to outerPlanet
+	for {
+		planetString, ok := mapOfOrbits[planet]
+		if ok {
+			// if the planet is found in the map, place the planet on the slice and continue to loop
+			planetsToComSlice = append(planetsToComSlice, planet)
+			planet = planetString
+		} else {
+			break
+		}
+	}
+
+	return planetsToComSlice
+}