day4 range overlappy thing

2022/day04/main.go

@@ -0,0 +1,90 @@
+package main
+
+import (
+	_ "embed"
+	"flag"
+	"fmt"
+	"strings"
+
+	"github.com/alexchao26/advent-of-code-go/cast"
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+//go:embed input.txt
+var input string
+
+func init() {
+	// do this in init (not main) so test file has same input
+	input = strings.TrimRight(input, "\n")
+	if len(input) == 0 {
+		panic("empty input.txt file")
+	}
+}
+
+func main() {
+	var part int
+	flag.IntVar(&part, "part", 1, "part 1 or 2")
+	flag.Parse()
+	fmt.Println("Running part", part)
+
+	if part == 1 {
+		ans := part1(input)
+		util.CopyToClipboard(fmt.Sprintf("%v", ans))
+		fmt.Println("Output:", ans)
+	} else {
+		ans := part2(input)
+		util.CopyToClipboard(fmt.Sprintf("%v", ans))
+		fmt.Println("Output:", ans)
+	}
+}
+
+func part1(input string) int {
+	lines := parseInput(input)
+	ans := 0
+
+	for _, l := range lines {
+		if doesPair2ContainPair1(l[:2], l[2:]) || doesPair2ContainPair1(l[2:], l[:2]) {
+			ans++
+		}
+	}
+
+	return ans
+}
+
+func doesPair2ContainPair1(pair1, pair2 []int) bool {
+	return pair1[0] >= pair2[0] && pair1[1] <= pair2[1]
+}
+
+func part2(input string) int {
+	lines := parseInput(input)
+	ans := 0
+
+	for _, l := range lines {
+		if doesOverlap(l[:2], l[2:]) {
+			ans++
+		}
+	}
+
+	return ans
+}
+
+func doesOverlap(pair1, pair2 []int) bool {
+	// sort
+	if pair1[0] > pair2[0] {
+		pair1, pair2 = pair2, pair1
+	}
+	return pair1[1] >= pair2[0]
+}
+
+func parseInput(input string) (ans [][]int) {
+	for _, line := range strings.Split(input, "\n") {
+		parts := strings.Split(line, ",")
+		leftParts := strings.Split(parts[0], "-")
+		rightParts := strings.Split(parts[1], "-")
+		ans = append(ans, []int{
+			cast.ToInt(leftParts[0]), cast.ToInt(leftParts[1]),
+			cast.ToInt(rightParts[0]), cast.ToInt(rightParts[1]),
+		})
+	}
+	return ans
+}