D1: implement a solution for puzzle part 1

day_1/day_1_.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strconv"
+)
+
+func main() {
+	inputFile, err := os.OpenFile("input", os.O_RDWR, 0666)
+	if err != nil {
+		log.Fatalf("error reading input data %v", err)
+	}
+	fmt.Printf("The elf with the most calories has %d calories", findMostCalories(inputFile))
+}
+
+func findMostCalories(input io.Reader) int {
+	r := bufio.NewScanner(input)
+	var maxSeen, calories int
+	for r.Scan() {
+		if r.Text() == "" {
+			if calories > maxSeen {
+				maxSeen = calories
+			}
+			calories = 0
+		} else {
+			toAdd, err := strconv.Atoi(r.Text())
+			if err != nil {
+				log.Fatalf("could not interpret data as calories: %v", err)
+			}
+			calories += toAdd
+		}
+	}
+	return maxSeen
+}

day_1/day_1_test.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestFindMostCalories(t *testing.T) {
+	t.Run("basic case", func(t *testing.T) {
+		input := strings.NewReader(`1000
+2000
+3000
+
+4000
+
+5000
+6000
+
+7000
+8000
+9000
+
+10000`)
+		answer := findMostCalories(input)
+		if answer != 24000 {
+			t.Errorf("want answer 24000, got %v", answer)
+		}
+	})
+}

day_1/go.mod

@@ -0,0 +1,3 @@
+module aoc_day_1
+
+go 1.19