AoC, Day 1, Part 2 (Solved)

2023/01/code.go

@@ -19,10 +19,89 @@ func main() {
 // 3. with: false (part1), and user input
 // 4. with: true (part2), and user input
 // the return value of each run is printed to stdout
+func testMatch(text string, match string, i int) bool {
+	if len(text)-i-len(match) < 0 {
+		return false
+	}
+
+	return text[i:i+len(match)] == match
+}
+
+func getNumber(text string, i int) rune {
+	if unicode.IsNumber(rune(text[i])) {
+		return rune(text[i])
+	} else {
+		// Might be a string
+		if testMatch(text, "one", i) {
+			return rune("1"[0])
+		}
+		if testMatch(text, "two", i) {
+			return rune("2"[0])
+		}
+		if testMatch(text, "three", i) {
+			return rune("3"[0])
+		}
+		if testMatch(text, "four", i) {
+			return rune("4"[0])
+		}
+		if testMatch(text, "five", i) {
+			return rune("5"[0])
+		}
+		if testMatch(text, "six", i) {
+			return rune("6"[0])
+		}
+		if testMatch(text, "seven", i) {
+			return rune("7"[0])
+		}
+		if testMatch(text, "eight", i) {
+			return rune("8"[0])
+		}
+		if testMatch(text, "nine", i) {
+			return rune("9"[0])
+		}
+	}
+	return rune("f"[0])
+}
+
 func run(part2 bool, input string) any {
 	// when you're ready to do part 2, remove this "not implemented" block
 	if part2 {
-		return "not implemented"
+
+		sum := 0
+		for _, line := range strings.Split(input, "\n") {
+			if line == "" {
+				continue
+			}
+			var firstChar rune
+			var secondChar rune
+
+			for i := range line {
+				if unicode.IsNumber(firstChar) && unicode.IsNumber(secondChar) {
+					break
+				}
+
+				if !unicode.IsNumber(firstChar) {
+					testFirst := getNumber(line, i)
+					if unicode.IsNumber(testFirst) {
+						firstChar = testFirst
+					}
+				}
+
+				if !unicode.IsNumber(secondChar) {
+					testSecond := getNumber(line, len(line)-1-i)
+					if unicode.IsNumber(testSecond) {
+						secondChar = testSecond
+					}
+				}
+			}
+
+			numberStr := fmt.Sprintf("%v%v", string(firstChar), string(secondChar))
+			number, _ := strconv.Atoi(numberStr)
+
+			sum += number
+		}
+
+		return sum
 	}
 
 	sum := 0