[2020-12-04] Add solutions for day04

Makefile

@@ -12,6 +12,8 @@ day03:
 	go run main.go day03 input
 
 day04:
+	go run main.go day04 input
+
 day05:
 day06:
 day07:

day04/example.txt

@@ -0,0 +1,13 @@
+ecl:gry pid:860033327 eyr:2020 hcl:#fffffd
+byr:1937 iyr:2017 cid:147 hgt:183cm
+
+iyr:2013 ecl:amb cid:350 eyr:2023 pid:028048884
+hcl:#cfa07d byr:1929
+
+hcl:#ae17e1 iyr:2013
+eyr:2024
+ecl:brn pid:760753108 byr:1931
+hgt:179cm
+
+hcl:#cfa07d eyr:2025 pid:166559648
+iyr:2011 ecl:brn hgt:59in

day04/parse.go

@@ -0,0 +1,33 @@
+package day04
+
+import (
+	"strings"
+
+	"git.elis.nu/etu/aoc2020/utils"
+)
+
+var rows []map[string]string
+
+func ParseFile(input string) {
+	row := make(map[string]string)
+
+	// Parse file
+	for _, line := range utils.GetLinesFromFile("day04/" + input + ".txt") {
+		if line == "" {
+			rows = append(rows, row)
+
+			row = make(map[string]string)
+
+			continue
+		}
+
+		for _, part := range strings.Split(line, " ") {
+			parts := strings.Split(part, ":")
+
+			row[parts[0]] = parts[1]
+		}
+	}
+
+	// Don't forget the last item
+	rows = append(rows, row)
+}

day04/solve1.go

@@ -0,0 +1,14 @@
+package day04
+
+import "log"
+
+func Solve1() {
+	counter := 0
+	for _, row := range rows {
+		if len(row) == 8 || len(row) == 7 && row["cid"] == "" {
+			counter++
+		}
+	}
+
+	log.Println("2020-12-04.01: Answer:", counter)
+}

day04/solve2.go

@@ -0,0 +1,50 @@
+package day04
+
+import (
+	"log"
+	"regexp"
+)
+
+func Solve2() {
+	counter := 0
+
+	validations := map[string]string{
+		// Validate Birth year (1920-2002)
+		"byr": `^(19[2-8][0-9]|199[0-9]|200[0-2])$`,
+
+		// Validate Issue year (2010-2020)
+		"iyr": `^(201[0-9]|2020)$`,
+
+		// Validate Expiration year (2020-2030)
+		"eyr": `^(202[0-9]|2030)$`,
+
+		// Validate height (59-76in) or (150-193cm)
+		"hgt": `^((59|6[0-9]|7[0-6])in|(1[5-8][0-9]|19[0-3])cm)$`,
+
+		// Validate Hair color
+		"hcl": `^#[0-9a-f]{6}$`,
+
+		// Validate Eye color
+		"ecl": `^(amb|blu|brn|gry|grn|hzl|oth)$`,
+
+		// Validate Passport ID
+		"pid": `^[0-9]{9}$`,
+	}
+
+	for _, row := range rows {
+		valid := true
+
+		for key, reg := range validations {
+			if regexp.MustCompile(reg).FindString(row[key]) == "" {
+				valid = false
+			}
+		}
+
+		if valid {
+			counter++
+		}
+	}
+
+	// Correct answer: 127
+	log.Println("2020-12-04.02: Answer:", counter)
+}

main.go

@@ -7,6 +7,7 @@ import (
 	"git.elis.nu/etu/aoc2020/day01"
 	"git.elis.nu/etu/aoc2020/day02"
 	"git.elis.nu/etu/aoc2020/day03"
+	"git.elis.nu/etu/aoc2020/day04"
 	"git.elis.nu/etu/aoc2020/utils"
 )
 
@@ -24,5 +25,8 @@ func main() {
 
 	case "day03":
 		utils.Perf("2020-12-03", day03.ParseFile, day03.Solve1, day03.Solve2)
+
+	case "day04":
+		utils.Perf("2020-12-04", day04.ParseFile, day04.Solve1, day04.Solve2)
 	}
 }