2021 - Day 2

2021/2/1/main.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	horizontal := 0
+	depth := 0
+
+	input, err := os.Open("input")
+	if err != nil {
+		panic(err)
+	}
+	defer input.Close()
+
+	scanner := bufio.NewScanner(input)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		re := regexp.MustCompile("[0-9]+")
+		if !re.MatchString(line) {
+			panic("Instruction does not contain number")
+		}
+
+		number, err := strconv.Atoi(re.FindString(line))
+
+		if err != nil {
+			panic(err)
+		}
+
+
+		if strings.HasPrefix(line, "forward") {
+			horizontal += number
+		} else if strings.HasPrefix(line, "up") {
+			depth -= number
+		} else if strings.HasPrefix(line, "down") {
+			depth += number
+		} else {
+			panic("Unknown instruction")
+		}
+	}
+
+	fmt.Println(horizontal, depth, horizontal*depth)
+
+	if err := scanner.Err(); err != nil {
+		panic(err)
+	}
+}
+