day 13

13/main.go

@@ -0,0 +1,143 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+)
+
+func mustAtoi(line string) int {
+	i, _ := strconv.Atoi(line)
+	return i
+}
+
+func main() {
+	start := time.Now()
+	partOne()
+	duration := time.Since(start)
+	partTwo()
+	duration2 := time.Since(start)
+	fmt.Printf("p1: %s, p2: %s\n", duration, duration2-duration)
+}
+
+func makeScanner(test bool) *bufio.Scanner {
+	var f *os.File
+	if test {
+		f, _ = os.Open("inputs/testinput")
+	} else {
+		f, _ = os.Open("inputs/input")
+	}
+	reader := bufio.NewReader(f)
+	return bufio.NewScanner(reader)
+}
+
+type point struct {
+	x int
+	y int
+}
+
+func partOne() {
+	scanner := makeScanner(false)
+
+	// parse points
+	points := make(map[point]struct{}, 0)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if line == "" {
+			break
+		}
+		p := strings.Split(line, ",")
+		points[point{
+			x: mustAtoi(p[0]),
+			y: mustAtoi(p[1]),
+		}] = struct{}{}
+	}
+
+	// make first fold
+	scanner.Scan()
+	f := strings.Split(scanner.Text(), "=")
+	orientation := strings.Split(f[0], " ")[2]
+	crease := mustAtoi(f[1])
+	if orientation == "y" {
+		for p := range points {
+			if p.y > crease {
+				delete(points, p)
+				points[point{x: p.x, y: p.y - ((p.y - crease) * 2)}] = struct{}{}
+			}
+		}
+	}
+	if orientation == "x" {
+		for p := range points {
+			if p.x > crease {
+				delete(points, p)
+				points[point{x: p.x - ((p.x - crease) * 2), y: p.y}] = struct{}{}
+			}
+		}
+	}
+	fmt.Println(len(points))
+}
+
+func partTwo() {
+	scanner := makeScanner(false)
+
+	// parse points
+	points := make(map[point]struct{}, 0)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if line == "" {
+			break
+		}
+		p := strings.Split(line, ",")
+		points[point{
+			x: mustAtoi(p[0]),
+			y: mustAtoi(p[1]),
+		}] = struct{}{}
+	}
+	// do folds
+	for scanner.Scan() {
+		line := scanner.Text()
+		f := strings.Split(line, "=")
+		orientation := strings.Split(f[0], " ")[2]
+		crease := mustAtoi(f[1])
+		if orientation == "y" {
+			for p := range points {
+				if p.y > crease {
+					delete(points, p)
+					points[point{x: p.x, y: p.y - ((p.y - crease) * 2)}] = struct{}{}
+				}
+			}
+		}
+		if orientation == "x" {
+			for p := range points {
+				if p.x > crease {
+					delete(points, p)
+					points[point{x: p.x - ((p.x - crease) * 2), y: p.y}] = struct{}{}
+				}
+			}
+		}
+	}
+	// find outer bounds of letters
+	maxy, maxx := 0, 0
+	for p := range points {
+		if p.y > maxy {
+			maxy = p.y
+		}
+		if p.x > maxx {
+			maxx = p.x
+		}
+	}
+	// print letters
+	for y := 0; y <= maxy; y++ {
+		for x := 0; x <= maxx; x++ {
+			if _, ok := points[point{x: x, y: y}]; ok {
+				fmt.Printf("#")
+			} else {
+				fmt.Printf(" ")
+			}
+		}
+		fmt.Printf("\n")
+	}
+}