2020 day04 string parsing and validation, regexp ^ and $ killed me

2020/day04/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"flag"
 	"fmt"
+	"regexp"
 	"strings"
 
 	"github.com/alexchao26/advent-of-code-go/util"
@@ -27,25 +28,121 @@ func main() {
 
 func part1(input string) int {
 	parsed := parseInput(input)
-	_ = parsed
 
-	return 0
-}
-
-func part2(input string) int {
-	parsed := parseInput(input)
-	_ = parsed
-
-	return 0
-}
-
-func parseInput(input string) []int {
-	var ans []int
-
-	lines := strings.Split(input, "\n")
-	for _, l := range lines {
-		ans = append(ans, util.StrToInt(l))
+	requiredFields := []string{
+		"byr",
+		"iyr",
+		"eyr",
+		"hgt",
+		"hcl",
+		"ecl",
+		"pid",
+		// "cid", // optional
+	}
+	var ans int
+	for _, entry := range parsed {
+		hasAllFields := true
+		for _, field := range requiredFields {
+			if entry[field] == "" {
+				hasAllFields = false
+				break
+			}
+		}
+		if hasAllFields {
+			ans++
+		}
 	}
 
 	return ans
 }
+
+func part2(input string) int {
+	passports := parseInput(input)
+
+	var ans int
+	for _, entry := range passports {
+		if validateFields(entry) {
+			ans++
+		}
+	}
+
+	return ans
+}
+
+func parseInput(input string) []map[string]string {
+	var passports []map[string]string
+
+	lines := strings.Split(input, "\n\n")
+
+	for _, l := range lines {
+		passportDetails := map[string]string{}
+
+		oneLine := strings.ReplaceAll(l, "\n", " ")
+		for _, entry := range strings.Split(oneLine, " ") {
+			splitEntry := strings.Split(entry, ":")
+			passportDetails[splitEntry[0]] = splitEntry[1]
+		}
+		passports = append(passports, passportDetails)
+	}
+
+	return passports
+}
+
+func validateFields(entry map[string]string) bool {
+	byr := entry["byr"]
+	if byr > "2002" || byr < "1920" || len(byr) != 4 {
+		return false
+	}
+
+	iyr := entry["iyr"]
+	if iyr > "2020" || iyr < "2010" || len(iyr) != 4 {
+		return false
+	}
+
+	eyr := entry["eyr"]
+	if eyr > "2030" || eyr < "2020" || len(eyr) != 4 {
+		return false
+	}
+
+	hgt := entry["hgt"]
+	if hgt == "" {
+		return false
+	}
+
+	var num int
+	var unit string
+	fmt.Sscanf(hgt, "%d%s", &num, &unit)
+
+	switch unit {
+	case "cm":
+		if num < 150 || num > 193 {
+			return false
+		}
+	case "in":
+		if num < 59 || num > 76 {
+			return false
+		}
+	default:
+		return false
+	}
+
+	hcl := entry["hcl"]
+	reg := regexp.MustCompile("^#[0-9a-f]{6}$")
+	if !reg.Match([]byte(hcl)) {
+		return false
+	}
+
+	ecl := entry["ecl"]
+	reg = regexp.MustCompile("^(amb|blu|brn|gry|grn|hzl|oth)$")
+	if !reg.Match([]byte(ecl)) {
+		return false
+	}
+
+	pid := entry["pid"]
+	reg = regexp.MustCompile("^[0-9]{9}$")
+	if !reg.Match([]byte(pid)) {
+		return false
+	}
+
+	return true
+}