2020 day 7 - graph traversal; parsed inputs way too slowly

2020/day07/main.go

@@ -16,36 +16,79 @@ func main() {
 
 	if part == 1 {
 		ans := part1(util.ReadFile("./input.txt"))
-		util.CopyToClipboard(fmt.Sprintf("%v", ans))
 		fmt.Println("Output:", ans)
 	} else {
 		ans := part2(util.ReadFile("./input.txt"))
-		util.CopyToClipboard(fmt.Sprintf("%v", ans))
 		fmt.Println("Output:", ans)
 	}
 }
 
 func part1(input string) int {
-	parsed := parseInput(input)
-	_ = parsed
+	graph := parseInput(input)
+	delete(graph, "shiny gold") // shouldn't be allowed in this graph just in case
 
-	return 0
+	var outers []string
+	// traverse edges until a "shiny gold bag" is found as a content?
+	for bag := range graph {
+		if dfsFindShinyGold(graph, bag) {
+			outers = append(outers, bag)
+		}
+	}
+
+	return len(outers)
 }
 
 func part2(input string) int {
-	parsed := parseInput(input)
-	_ = parsed
+	graph := parseInput(input)
 
-	return 0
+	// subtract one for the shiny gold bag counting itself
+	return countSubbags(graph, "shiny gold") - 1
 }
 
-func parseInput(input string) []int {
-	var ans []int
+// not a fun input to parse through, there has to be a better way to do this in go...
+func parseInput(input string) map[string]map[string]int {
+	graph := map[string]map[string]int{}
+	for _, line := range strings.Split(input, "\n") {
+		split := strings.Split(line, " contain ")
+		color := split[0][:strings.Index(split[0], " bags")]
+		graph[color] = map[string]int{}
 
-	lines := strings.Split(input, "\n")
-	for _, l := range lines {
-		ans = append(ans, util.StrToInt(l))
+		for _, content := range strings.Split(split[1], ", ") {
+			if content == "no other bags." {
+				continue
+			}
+			parts := strings.Split(content, " ")
+			graph[color][parts[1]+" "+parts[2]] = util.StrToInt(parts[0])
+		}
+	}
+	return graph
+}
+
+func dfsFindShinyGold(graph map[string]map[string]int, entry string) bool {
+	// shiny gold is contained within this bag, return true & collapse call stack
+	if _, ok := graph[entry]["shiny gold"]; ok {
+		return true
 	}
 
-	return ans
+	// otherwise traverse into its edges and if it returns true, send down callstack
+	for subBags := range graph[entry] {
+		if dfsFindShinyGold(graph, subBags) {
+			return true
+		}
+	}
+
+	// otherwise shiny gold was not reached, just return false
+	return false
+}
+
+func countSubbags(graph map[string]map[string]int, entry string) int {
+	// count itself
+	bags := 1
+
+	// traverse into its subbags and add time its count
+	for subBag, count := range graph[entry] {
+		bags += count * countSubbags(graph, subBag)
+	}
+
+	return bags
 }