2021 Day 13 Complete!

2021/day13/main.go

@@ -0,0 +1,79 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	dots := h.CoordByteMap{
+		Field: make(map[h.Coordinate]byte),
+	}
+	var folds []h.Coordinate
+
+	var inst bool
+	for i := range inp {
+		if inst {
+			// folding instructions
+			pts := strings.Split(inp[i], "=")
+			v := h.Atoi(pts[1])
+			if pts[0][len(pts[0])-1] == 'x' {
+				folds = append(folds, h.Coordinate{X: v, Y: -1})
+			} else {
+				folds = append(folds, h.Coordinate{X: -1, Y: v})
+			}
+		} else if inp[i] == "" {
+			inst = true
+		} else {
+			// A dot
+			pts := strings.Split(inp[i], ",")
+			c := h.Coordinate{X: h.Atoi(pts[0]), Y: h.Atoi(pts[1])}
+			dots.Put(c, '#')
+		}
+	}
+	fmt.Println("# Part 1")
+	fmt.Println(len(doFolds(dots, []h.Coordinate{folds[0]}).Field))
+	fmt.Println()
+	fmt.Println("# Part 2")
+	dots = doFolds(dots, folds)
+	fmt.Println("Total Dots:", len(dots.Field))
+	for y := 0; y < dots.Height; y++ {
+		for x := 0; x < dots.Width; x++ {
+			b := dots.Get(h.Coordinate{X: x, Y: y})
+			if b != 0 {
+				fmt.Print("▓")
+			} else {
+				fmt.Print(" ")
+			}
+		}
+		fmt.Print("\n")
+	}
+}
+
+func doFolds(dots h.CoordByteMap, folds []h.Coordinate) h.CoordByteMap {
+	for i := range folds {
+		newDots := h.CoordByteMap{
+			Field: make(map[h.Coordinate]byte),
+		}
+		if folds[i].X != -1 {
+			for k := range dots.Field {
+				if k.X > folds[i].X {
+					k.X = folds[i].X - (k.X - folds[i].X)
+				}
+				newDots.Put(k, '#')
+			}
+		} else if folds[i].Y != -1 {
+			for k := range dots.Field {
+				if k.Y > folds[i].Y {
+					k.Y = folds[i].Y - (k.Y - folds[i].Y)
+				}
+				newDots.Put(k, '#')
+			}
+		}
+		dots = newDots
+	}
+	return dots
+}