feat: add 2018D3 dataset

cmd/aoc/main.go

@@ -17,6 +17,7 @@ import (
 
 	// 2018
 	_ "advent-of-code/internal/2018/DayOne"
+	_ "advent-of-code/internal/2018/DayThree"
 	_ "advent-of-code/internal/2018/DayTwo"
 
 	// 2020

internal/2018/DayThree/code.go

@@ -0,0 +1,101 @@
+package daythree
+
+import (
+	"advent-of-code/internal/registry"
+	"fmt"
+	"os"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+func init() {
+	registry.Register("2018D3", ParseInput, PartOne, PartTwo)
+}
+
+func ParseInput(filepath string) []string {
+	content, _ := os.ReadFile(filepath)
+	return strings.Split(string(content), "\n")
+}
+
+func PartOne(data []string) int {
+	coverage := make(map[string]int)
+	re := regexp.MustCompile(`#\d+ @ (\d+),(\d+): (\d+)x(\d+)`)
+
+	for _, line := range data {
+		matches := re.FindStringSubmatch(line)
+
+		left, _ := strconv.Atoi(matches[1])
+		top, _ := strconv.Atoi(matches[2])
+		width, _ := strconv.Atoi(matches[3])
+		height, _ := strconv.Atoi(matches[4])
+
+		for x := left; x < left+width; x++ {
+			for y := top; y < top+height; y++ {
+				key := fmt.Sprintf("%d,%d", x, y)
+				coverage[key]++
+			}
+		}
+	}
+
+	overlapCount := 0
+	for _, count := range coverage {
+		if count >= 2 {
+			overlapCount++
+		}
+	}
+
+	return overlapCount
+}
+
+func PartTwo(data []string) int {
+	coverage := make(map[string]int)
+	re := regexp.MustCompile(`#\d+ @ (\d+),(\d+): (\d+)x(\d+)`)
+
+	for _, line := range data {
+		matches := re.FindStringSubmatch(line)
+
+		left, _ := strconv.Atoi(matches[1])
+		top, _ := strconv.Atoi(matches[2])
+		width, _ := strconv.Atoi(matches[3])
+		height, _ := strconv.Atoi(matches[4])
+
+		for x := left; x < left+width; x++ {
+			for y := top; y < top+height; y++ {
+				key := fmt.Sprintf("%d,%d", x, y)
+				coverage[key]++
+			}
+		}
+	}
+
+	reWithID := regexp.MustCompile(`#(\d+) @ (\d+),(\d+): (\d+)x(\d+)`)
+	for _, line := range data {
+		matches := reWithID.FindStringSubmatch(line)
+		if len(matches) != 6 {
+			continue
+		}
+
+		id, _ := strconv.Atoi(matches[1])
+		left, _ := strconv.Atoi(matches[2])
+		top, _ := strconv.Atoi(matches[3])
+		width, _ := strconv.Atoi(matches[4])
+		height, _ := strconv.Atoi(matches[5])
+
+		overlaps := false
+		for x := left; x < left+width && !overlaps; x++ {
+			for y := top; y < top+height; y++ {
+				key := fmt.Sprintf("%d,%d", x, y)
+				if coverage[key] > 1 {
+					overlaps = true
+					break
+				}
+			}
+		}
+
+		if !overlaps {
+			return id
+		}
+	}
+
+	return 0
+}

internal/2018/DayThree/code_test.go

@@ -0,0 +1,25 @@
+package daythree
+
+import "testing"
+
+var testInput = []string{
+	"#1 @ 1,3: 4x4",
+	"#2 @ 3,1: 4x4",
+	"#3 @ 5,5: 2x2",
+}
+
+func TestPartOne(t *testing.T) {
+	expected := 4
+	got := PartOne(testInput)
+	if got != expected {
+		t.Errorf("PartOne() = %d, want %d", got, expected)
+	}
+}
+
+func TestPartTwo(t *testing.T) {
+	expected := 3
+	got := PartTwo(testInput)
+	if got != expected {
+		t.Errorf("PartTwo() = %d, want %d", got, expected)
+	}
+}