2023 Day 18 Complete!

2023/day18/main.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	part1(inp)
+	fmt.Println()
+	part2(inp)
+}
+
+func part1(input []string) {
+	dirMap := map[byte]h.Coordinate{
+		'U': h.Coordinate{X: 0, Y: -1},
+		'R': h.Coordinate{X: 1, Y: 0},
+		'D': h.Coordinate{X: 0, Y: 1},
+		'L': h.Coordinate{X: -1, Y: 0},
+	}
+
+	curr, area := h.Coordinate{X: 0, Y: 0}, 0
+	for i := range input {
+		pts := strings.Fields(input[i])
+		dir, length, _ := pts[0][0], h.Atoi(pts[1]), strings.Trim(pts[1], "()")
+		n := curr.Add(dirMap[dir].Mul(length))
+		area += curr.X*n.Y - curr.Y*n.X + length
+		curr = n
+	}
+	fmt.Println("# Part 1")
+	fmt.Println(area/2 + 1)
+}
+
+func part2(input []string) {
+	dirMap := map[byte]h.Coordinate{
+		'3': h.Coordinate{X: 0, Y: -1},
+		'0': h.Coordinate{X: 1, Y: 0},
+		'1': h.Coordinate{X: 0, Y: 1},
+		'2': h.Coordinate{X: -1, Y: 0},
+	}
+
+	hexToDec := func(hex string) int {
+		v, _ := strconv.ParseInt(hex, 16, strconv.IntSize)
+		return int(v)
+	}
+	curr, area := h.Coordinate{X: 0, Y: 0}, 0
+	for i := range input {
+		pts := strings.Fields(input[i])
+		pts[2] = strings.Trim(pts[2], "#()")
+		length := hexToDec(pts[2][:len(pts[2])-1])
+		dir := pts[2][len(pts[2])-1:][0]
+
+		n := curr.Add(dirMap[dir].Mul(length))
+		area += curr.X*n.Y - curr.Y*n.X + length
+		curr = n
+	}
+	fmt.Println("# Part 2")
+	fmt.Println(area/2 + 1)
+}