add day-21 + benchmarks

day-21/internal/one/benchmark

@@ -0,0 +1,6 @@
+goos: linux
+goarch: amd64
+pkg: github.com/onyx-and-iris/aoc2024/day-21/internal/one
+cpu: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
+BenchmarkSolve-12    	1000000000	         0.0000606 ns/op
+ok  	github.com/onyx-and-iris/aoc2024/day-21/internal/one	0.008s

day-21/internal/one/solve.go

@@ -0,0 +1,36 @@
+package one
+
+import (
+	"bytes"
+
+	"github.com/onyx-and-iris/aoc2024/day-21/internal/pad"
+	log "github.com/sirupsen/logrus"
+)
+
+func Solve(buf []byte) (int, error) {
+	r := bytes.NewReader(buf)
+	codes, err := parseLines(r)
+	if err != nil {
+		return 0, err
+	}
+
+	numpad := pad.NewNumpad()
+	dirpad := pad.NewDirpad()
+
+	var complexity int
+	for _, code := range codes {
+		moves := generateMoves(numpad, dirpad, code)
+		complexity += len(moves) * numFromCode(code)
+		log.Debugf("%s\n%d * %d\n", moves, len(moves), numFromCode(code))
+	}
+
+	return complexity, nil
+}
+
+type generator interface {
+	Generate(code string) string
+}
+
+func generateMoves(n, d generator, code string) string {
+	return d.Generate(d.Generate(n.Generate(code)))
+}

day-21/internal/one/solve_internal_test.go

@@ -0,0 +1,15 @@
+package one
+
+import (
+	_ "embed"
+	"os"
+	"testing"
+)
+
+//go:embed testdata/input.txt
+var data []byte
+
+func BenchmarkSolve(b *testing.B) {
+	os.Stdout, _ = os.Open(os.DevNull)
+	Solve(data)
+}

day-21/internal/one/util.go

@@ -0,0 +1,27 @@
+package one
+
+import (
+	"bufio"
+	"io"
+	"strconv"
+)
+
+func parseLines(r io.Reader) ([]string, error) {
+	codes := []string{}
+
+	scanner := bufio.NewScanner(r)
+	for scanner.Scan() {
+		codes = append(codes, scanner.Text())
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return codes, nil
+}
+
+func numFromCode(s string) int {
+	n, _ := strconv.Atoi(s[:len(s)-1])
+	return n
+}