2020 day2 - string parsing & simple validation

2020/day02/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"flag"
 	"fmt"
+	"strings"
 
 	"github.com/alexchao26/advent-of-code-go/util"
 )
@@ -23,9 +24,58 @@ func main() {
 }
 
 func part1(input string) int {
-	return 0
+	lines := strings.Split(input, "\n")
+
+	var ans int
+
+	for _, l := range lines {
+		var lower, upper int
+		var char, pw string
+
+		_, err := fmt.Sscanf(l, "%d-%d %1s: %s", &lower, &upper, &char, &pw)
+		if err != nil {
+			panic("scanning line " + err.Error())
+		}
+
+		count := 0
+		for _, v := range pw {
+			if string(v) == char {
+				count++
+			}
+		}
+		if count <= upper && count >= lower {
+			ans++
+		}
+	}
+
+	return ans
 }
 
 func part2(input string) int {
-	return 0
+	lines := strings.Split(input, "\n")
+
+	var ans int
+	for _, l := range lines {
+		var lower, upper int
+		var char, pw string
+
+		_, err := fmt.Sscanf(l, "%d-%d %1s: %s", &lower, &upper, &char, &pw)
+		if err != nil {
+			panic("scanning line " + err.Error())
+		}
+
+		count := 0
+		if string(pw[lower-1]) == char {
+			count++
+		}
+		if string(pw[upper-1]) == char {
+			count++
+		}
+
+		if count == 1 {
+			ans++
+		}
+	}
+
+	return ans
 }