2020 Day 7 Complete!

2020/day07/main.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	fmt.Println("# Day 7")
+	inp := h.StdinToStringSlice()
+
+	allBags := make(map[string]*Bag)
+	for _, v := range inp {
+		b := ParseBag(v)
+		allBags[b.Color] = b
+	}
+	// Now fill in all 'contains'
+	for _, v := range allBags {
+		for _, cc := range v.ContainsColors {
+			v.Contains = append(v.Contains, allBags[cc])
+		}
+	}
+	whatIGot := "shiny gold"
+	var bagsCanContain int
+	for _, v := range allBags {
+		if v.CanContain(whatIGot) {
+			bagsCanContain++
+		}
+	}
+	fmt.Println("## Part 1")
+	fmt.Printf("My %s bag can be held by %d bags\n\n", whatIGot, bagsCanContain)
+	fmt.Println("## Part 2")
+	fmt.Printf("And my bag must contain %d other bags\n", allBags[whatIGot].CountBagsInside())
+}
+
+type Bag struct {
+	Color          string
+	ContainsColors []string
+	Contains       []*Bag
+}
+
+func ParseBag(inp string) *Bag {
+	ret := Bag{}
+	pts := strings.Split(inp, " bags contain ")
+	ret.Color = pts[0]
+	pts[1] = strings.ReplaceAll(pts[1], "bags", "")
+	pts[1] = strings.ReplaceAll(pts[1], "bag", "")
+	pts[1] = pts[1][:len(pts[1])-2]
+	nest := strings.Split(pts[1], ", ")
+	for _, v := range nest {
+		space := strings.Index(v, " ")
+		num, rest := v[:space], strings.TrimSpace(v[space:])
+		if num != "no" {
+			count := h.Atoi(num)
+			for count > 0 {
+				ret.ContainsColors = append(ret.ContainsColors, rest)
+				count--
+			}
+		}
+	}
+	return &ret
+}
+
+func (b *Bag) CanContain(color string) bool {
+	for _, v := range b.ContainsColors {
+		if v == color {
+			return true
+		}
+	}
+	for _, v := range b.Contains {
+		if v.CanContain(color) {
+			return true
+		}
+	}
+	return false
+}
+
+func (b *Bag) CountBagsInside() int {
+	ret := len(b.Contains)
+	for _, v := range b.Contains {
+		ret = ret + v.CountBagsInside()
+	}
+	return ret
+}