Add usage instructions in README.md

README.md

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+# Usage
+1. Change directory to chosen day
+2. `go run dayXX.go < input.txt`

day02/day2.go

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+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+type Limitations struct {
+	red   int
+	blue  int
+	green int
+}
+
+type Draw struct {
+	red   int
+	blue  int
+	green int
+}
+
+type Game struct {
+	id    int
+	draws []Draw
+	meta  Meta
+}
+
+type Meta struct {
+	possible  bool
+	red_min   int
+	green_min int
+	blue_min  int
+}
+
+func readInput() string {
+	stdin, err := io.ReadAll(os.Stdin)
+
+	if err != nil {
+		panic(err)
+	}
+	str := string(stdin)
+	return str
+}
+
+func getColors(input string, color string) string {
+	rg := regexp.MustCompile(`[0-9]+ ` + regexp.QuoteMeta(color))
+	return rg.FindString(input)
+}
+
+func parseGameLine(line string, limits Limitations) Game {
+	splitted := strings.Split(line, ":")
+	draws_splitted := strings.Split(splitted[1], ";")
+	game_prefix := splitted[0]
+
+	id, _ := strconv.Atoi(strings.Split(game_prefix, " ")[1])
+	draws := []Draw{}
+	meta := Meta{}
+	red_min, green_min, blue_min := 0, 0, 0
+	meta.possible = true
+	for _, v := range draws_splitted {
+		red, _ := strconv.Atoi(strings.Split(getColors(v, "red"), " ")[0])
+		green, _ := strconv.Atoi(strings.Split(getColors(v, "green"), " ")[0])
+		blue, _ := strconv.Atoi(strings.Split(getColors(v, "blue"), " ")[0])
+		if (red > limits.red) || (green > limits.green) || (blue > limits.blue) {
+			meta.possible = false
+		}
+		if red_min < red {
+			red_min = red
+		}
+		if green_min < green {
+			green_min = green
+		}
+		if blue_min < blue {
+			blue_min = blue
+		}
+		draw := Draw{
+			red:   red,
+			blue:  blue,
+			green: green,
+		}
+		draws = append(draws, draw)
+	}
+	meta.blue_min = blue_min
+	meta.red_min = red_min
+	meta.green_min = green_min
+	game := Game{
+		id:    id,
+		draws: draws,
+		meta:  meta,
+	}
+
+	// fmt.Println(game)
+	return game
+}
+
+func part1(lines []string) {
+	limits := Limitations{
+		red:   12,
+		green: 13,
+		blue:  14,
+	}
+	var games []Game
+	sum_ids := 0
+	for _, l := range lines {
+		if len(l) == 0 {
+			continue
+		}
+		game := parseGameLine(l, limits)
+		if game.meta.possible {
+			games = append(games, game)
+			sum_ids += game.id
+		}
+	}
+
+	fmt.Println("Sum ids:", sum_ids)
+}
+
+func part2(lines []string) {
+	var games []Game
+
+	for _, l := range lines {
+		if len(l) == 0 {
+			continue
+		}
+		game := parseGameLine(l, Limitations{})
+		games = append(games, game)
+	}
+	sum := 0
+	for _, g := range games {
+		sum += (g.meta.red_min * g.meta.green_min * g.meta.blue_min)
+	}
+	fmt.Println(sum)
+}
+
+func main() {
+	input := readInput()
+	lines := strings.Split(input, "\n")
+	fmt.Println("---PART 1---")
+	part1(lines)
+	fmt.Println("---PART 2---")
+	part2(lines)
+}

day02/example.txt

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+Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green

day_template/day.go

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+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+)
+
+func readInput() string {
+	stdin, err := io.ReadAll(os.Stdin)
+
+	if err != nil {
+		panic(err)
+	}
+	str := string(stdin)
+	return str
+}
+
+func part1(lines []string) {
+	fmt.Println("Part 1 not implemented")
+}
+
+func part2(lines []string) {
+	fmt.Println("Part 2 not implemented")
+}
+
+func main() {
+	input := readInput()
+	lines := strings.Split(input, "\n")
+	fmt.Println("---PART 1---")
+	part1(lines)
+	fmt.Println("---PART 2---")
+	part2(lines)
+}

go.work

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+go 1.21.5

new_day.sh

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+#!/bin/sh
+# Code borrowed from https://github.com/Daste745/aoc-2023/blob/master/new_day.sh
+if [ -z "$1" ]
+then
+  cat << EOF
+Usage: new_day.sh <day_number>
+
+Example: new_day.sh 08
+EOF
+  exit 1
+fi
+
+day_number=$1
+if [ -d "day$day_number" ]
+then
+  echo "Day$day_number already exists"
+  exit 1
+fi
+
+mkdir -p ./day$day_number/
+cp -v ./day_template/day.go ./day$day_number/day$day_number.go
+