Added the first days

2021/02/second.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	f, err := os.Open("input")
+	if err != nil {
+		log.Fatalf("%+v", err)
+	}
+	defer f.Close()
+
+	scanner := bufio.NewScanner(f)
+	scanner.Split(bufio.ScanLines)
+
+	aim := 0
+	pos := 0
+	depth := 0
+	for scanner.Scan() {
+		elts := strings.Split(scanner.Text(), " ")
+		i, err := strconv.Atoi(elts[1])
+		if err != nil {
+			log.Fatalf("%+v", err)
+		}
+		switch elts[0] {
+		case "forward":
+			pos += i
+			depth += i * aim
+		case "down":
+			aim += i
+		case "up":
+			aim -= i
+		default:
+			panic(elts[0])
+		}
+	}
+	fmt.Println(pos * depth)
+}