Added the first days

2021/03/first.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+)
+
+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)
+
+	bits := make([]int, 12)
+	for scanner.Scan() {
+		num := scanner.Text()
+		for n := 0; n < 12; n++ {
+			if num[n] == '1' {
+				bits[n]++
+			}
+		}
+	}
+
+	gamma := 0
+	epsilon := 0
+	for n := 0; n < 12; n++ {
+		gamma *= 2
+		epsilon *= 2
+		if bits[n] > 500 {
+			gamma++
+		} else {
+			epsilon++
+		}
+	}
+	fmt.Println(gamma * epsilon)
+}