Solved for sample, not for input

03/code.go

@@ -23,6 +23,81 @@ func readInput(file *os.File) []string {
 	return lines
 }
 
+const firstDigit = 48
+const lastDigit = 57
+
+func isDigit(b byte) bool {
+	return firstDigit <= b && b <= lastDigit
+}
+
+func isSymbol(b byte) bool {
+	return !isDigit(b) && b != '.'
+}
+
+func symbolNear(lines []string, height int, width int, y int, start int, end int) bool {
+	i := start - 1
+	if i < 0 {
+		i = start
+	}
+
+	canGoUp := y-1 >= 0
+	canGoDown := y+1 < height
+
+	for ; i <= end; i++ {
+		if isSymbol(lines[y][i]) {
+			return true
+		}
+
+		if canGoUp && isSymbol(lines[y-1][i]) {
+			return true
+		}
+
+		if canGoDown && isSymbol(lines[y+1][i]) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func part1(lines []string) int {
+	var result int
+	height := len(lines)
+	width := len(lines[0])
+	for i := range lines {
+		var start, end int
+		gotNumber := false
+		for j := range lines[i] {
+			if lines[i][j] == '.' {
+				if !gotNumber {
+					continue
+				}
+
+				end = j
+				gotNumber = false
+				if symbolNear(lines, height, width, i, start, end) {
+					var d int
+					n, err := fmt.Sscanf(lines[i][start:end], "%d", &d)
+					if n != 1 || err != nil {
+						log.Fatalf("Wrong input: %s\n%s", lines[i][start:end], err)
+					}
+
+					result += d
+				}
+			}
+
+			if isDigit(lines[i][j]) {
+				if !gotNumber {
+					start = j
+					gotNumber = true
+				}
+			}
+		}
+	}
+
+	return result
+}
+
 func main() {
 	if len(os.Args) < 2 {
 		log.Fatal("You need to specify a file!")
@@ -36,5 +111,5 @@ func main() {
 	}
 
 	lines := readInput(file)
-	fmt.Println(lines)
+	fmt.Println("Part1:", part1(lines))
 }

03/input

@@ -0,0 +1,140 @@
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