day 1a

day01/day01.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func getCalibrationValue(input string) int {
+	firstIdx := strings.IndexAny(input, "0123456789")
+	lastIdx := strings.LastIndexAny(input, "0123456789")
+	first := string([]rune(input)[firstIdx])
+	last := string([]rune(input)[lastIdx])
+	output, _ := strconv.Atoi(first + last)
+	return output
+}
+
+func ScanFile(file *os.File) (int, error) {
+	scanner := bufio.NewScanner(file);
+	sum := 0;
+    for scanner.Scan() {
+        sum += getCalibrationValue(scanner.Text());
+    }
+    if err := scanner.Err(); err != nil {
+        return 0, err
+    }
+	return sum, nil
+}
+
+func main() {
+	sum, err := ScanFile(os.Stdin)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Invalid input: %s\n", err)
+		return
+	}
+	fmt.Println(sum)
+}