add day 1 and 2 solutions

day02/internal/parser/parser.go

@@ -0,0 +1,48 @@
+package parser
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const DefaultFile = "input"
+
+func ParseFile(input *string) ([]int, error) {
+	if input == nil {
+
+		file := DefaultFile
+
+		if len(os.Args) == 2 {
+			file = os.Args[1]
+		}
+
+		inputFile, err := os.Open(file)
+		if err != nil {
+			return nil, fmt.Errorf("could not parse input file: %v", err)
+		}
+
+		fileData, err := io.ReadAll(inputFile)
+		if err != nil {
+			return nil, fmt.Errorf("could not read input file: %v", err)
+		}
+
+		fileStr := strings.TrimSpace(string(fileData))
+		input = &fileStr
+	}
+
+	strNums := strings.Split(*input, ",")
+	opcodes := make([]int, len(strNums))
+
+	for i, v := range strNums {
+		num, err := strconv.Atoi(v)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "WARNING: error parsing int from input, substring was %v", v)
+		}
+		opcodes[i] = num
+	}
+
+	return opcodes, nil
+}