commit 36746b69e4913315ff0de8aec569639b776ab621
Author: Stefan Harmuth <stefan.harmuth@docomodigital.com>
Date:   Mon Dec 21 21:12:33 2020 +0100

    copy from aoc2020

diff --git a/aoclib/aoclib.go b/aoclib/aoclib.go
new file mode 100644
index 0000000..392b05e
--- /dev/null
+++ b/aoclib/aoclib.go
@@ -0,0 +1,80 @@
+package aoclib
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"time"
+)
+
+type Puzzle struct {
+	FromFile    string
+	RawInput    []string
+	RawInputInt []int
+}
+
+func (p *Puzzle) ReadInputFromFile() {
+	fh, err := os.Open(p.FromFile)
+	if err != nil {
+		log.Fatal("fopen error:", err)
+	}
+	defer fh.Close()
+
+	p.RawInput = []string{}
+	scanner := bufio.NewScanner(fh)
+	for scanner.Scan() {
+		p.RawInput = append(p.RawInput, scanner.Text())
+	}
+
+	if err := scanner.Err(); err != nil {
+		log.Fatal("scanner error:", err)
+	}
+}
+
+func (p *Puzzle) GetInputArray() []string {
+	if len(p.RawInput) == 0 && len(p.FromFile) != 0 {
+		p.ReadInputFromFile()
+	}
+
+	return p.RawInput
+}
+
+func (p *Puzzle) GetInputArrayInt() []int {
+	if len(p.RawInputInt) == 0 {
+		for _, v := range p.GetInputArray() {
+			value, err := strconv.Atoi(v)
+			if err != nil {
+				log.Fatal("Cannot convert string to int:", v)
+			} else {
+				p.RawInputInt = append(p.RawInputInt, value)
+			}
+		}
+	}
+
+	return p.RawInputInt
+}
+
+func (p Puzzle) Solve(partFunction func(p Puzzle) interface{}, day int, part int, timeit bool, timeitNumber int) {
+	var result interface{}
+	if !timeit {
+		result = partFunction(p)
+		fmt.Printf(
+			"Result for day %d, part %d: %#v\n",
+			day, part, result,
+		)
+	} else {
+		start := time.Now()
+		for i := 0; i < timeitNumber; i++ {
+			result = partFunction(p)
+		}
+		elapsed := time.Duration(int64(time.Since(start)) / int64(timeitNumber))
+
+		fmt.Printf(
+			"Result for day %d, part %d: %#v (avg over %d runs: %s)\n",
+			day, part, result, timeitNumber, elapsed,
+		)
+	}
+
+}
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..f322a3c
--- /dev/null
+++ b/main.go
@@ -0,0 +1,79 @@
+package main
+
+import (
+	"aoc2020/aoclib"
+	"aoc2020/day01"
+	"aoc2020/day02"
+	"aoc2020/day03"
+	"aoc2020/day17"
+	"aoc2020/day18"
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+var dayFunctions map[int]map[int]func(puzzle aoclib.Puzzle) interface{}
+var day int
+var part int
+var test bool
+var timeit bool
+var timeitNumber int
+var myDir, _ = filepath.Abs(filepath.Dir(os.Args[0]))
+
+func initDayFunctions() {
+	dayFunctions = make(map[int]map[int]func(puzzle aoclib.Puzzle) interface{})
+	dayFunctions[1] = make(map[int]func(puzzle aoclib.Puzzle) interface{})
+	dayFunctions[1][1] = day01.Part1
+	dayFunctions[1][2] = day01.Part2
+	dayFunctions[2] = make(map[int]func(puzzle aoclib.Puzzle) interface{})
+	dayFunctions[2][1] = day02.Part1
+	dayFunctions[2][2] = day02.Part2
+	dayFunctions[3] = make(map[int]func(puzzle aoclib.Puzzle) interface{})
+	dayFunctions[3][1] = day03.Part1
+	dayFunctions[3][2] = day03.Part2
+	dayFunctions[17] = make(map[int]func(puzzle aoclib.Puzzle) interface{})
+	dayFunctions[17][1] = day17.Part1
+	dayFunctions[17][2] = day17.Part2
+	dayFunctions[18] = make(map[int]func(puzzle aoclib.Puzzle) interface{})
+	dayFunctions[18][1] = day18.Part1
+	dayFunctions[18][2] = day18.Part2
+}
+
+func execute(thisDay int) {
+	p := aoclib.Puzzle{}
+	if test {
+		p.FromFile = fmt.Sprintf("%s/inputs/%d_test", myDir, thisDay)
+	} else {
+		p.FromFile = fmt.Sprintf("%s/inputs/%d", myDir, thisDay)
+	}
+	p.ReadInputFromFile()
+	if part == -1 || part == 1 {
+		p.Solve(dayFunctions[thisDay][1], thisDay, 1, timeit, timeitNumber)
+	}
+	if part == -1 || part == 2 {
+		p.Solve(dayFunctions[thisDay][2], thisDay, 2, timeit, timeitNumber)
+	}
+}
+
+func main() {
+	initDayFunctions()
+	flag.IntVar(&day, "day", -1, "day to execute; -1 = all")
+	flag.IntVar(&part, "part", -1, "part to execute; -1 = all")
+	flag.BoolVar(&test, "test", false, "run the test case")
+	flag.BoolVar(&timeit, "timeit", false, "measure execution time")
+	flag.IntVar(&timeitNumber, "timeitNumber", 50, "build time average of this many runs")
+	flag.Parse()
+
+	if day != -1 {
+		if _, ok := dayFunctions[day]; !ok {
+			fmt.Printf("ERROR: unknown/invalid day: %d\n", day)
+			os.Exit(1)
+		}
+		execute(day)
+	} else {
+		for thisDay := range dayFunctions {
+			execute(thisDay)
+		}
+	}
+}