added 03/01

03/main.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var (
+	inputFile = flag.String("input", "input.txt", "input filename")
+	digRegex  = regexp.MustCompile(`(?m)\d+`)
+)
+
+func NearSymbols(line string, lineLen int, pos []int) (symbols int) {
+	// fmt.Printf("looking at %s, line-length=%d\n", line[pos[0]:pos[1]], lineLen)
+	for i := pos[0] + lineLen - 1; i < (pos[1] + lineLen + 1); i++ {
+		if i < 0 || i >= len(line) {
+			// fmt.Printf("skipped invalid index %d (len=%d)\n", i, len(line))
+			continue
+		}
+
+		// fmt.Println("looking at " + string(line[i]))
+
+		if line[i] != '.' && line[i] != '\n' && (line[i] < 48 || line[i] > 57) {
+			fmt.Printf("found %s\n", string(line[i]))
+			symbols++
+		}
+	}
+	return
+}
+
+func main() {
+	flag.Parse()
+	input, err := os.ReadFile(*inputFile)
+	if err != nil {
+		panic(err)
+	}
+
+	var sum int
+	strIn := string(input)
+	lineLen := strings.Index(strIn, "\n") + 1
+	allNumbers := digRegex.FindAllStringIndex(strIn, -1)
+
+	for _, numMatch := range allNumbers {
+		symbols := 0
+		symbols += NearSymbols(strIn, lineLen*-1, numMatch)
+		symbols += NearSymbols(strIn, 0, numMatch)
+		symbols += NearSymbols(strIn, lineLen, numMatch)
+
+		if symbols > 0 {
+			numberAsInt, err := strconv.Atoi(strIn[numMatch[0]:numMatch[1]])
+			if err != nil {
+				panic(err)
+			}
+			sum += numberAsInt
+			fmt.Printf("%d matched with %d symbols\n", numberAsInt, symbols)
+		}
+	}
+
+	fmt.Printf("sum: %d\n", sum)
+}