day 9 part 1

main.go

@@ -30,6 +30,9 @@ func main() {
 
 	runAndBenchmark("08", "1", false, solutions.Day08Part01)
 	runAndBenchmark("08", "2", false, solutions.Day08Part02)
+
+	runAndBenchmark("09", "1", false, solutions.Day09Part01)
+	runAndBenchmark("09", "2", true, solutions.Day09Part02)
 }
 
 type execute func(bool) int

solutions/day09.go

@@ -0,0 +1,60 @@
+package solutions
+
+import (
+	"strconv"
+	"strings"
+)
+
+func Day09Part01(isTest bool) int {
+	input := ReadInput("09", isTest)
+	groups := strings.Split(input, "\n")
+
+	dataSize := len(groups)
+	numbers := make([]int, dataSize)
+
+	for i, str := range groups {
+		value, err := strconv.Atoi(str)
+		if err != nil {
+			panic(err)
+		}
+
+		numbers[i] = value
+	}
+
+	// loop
+	preambleSize := 25
+
+out:
+	for i := 0; i < dataSize-preambleSize; i += 1 {
+		sum := numbers[i+preambleSize]
+		// A slice that stores: sum - i
+		indexes := make([]int, preambleSize)
+
+		// Iterate over every `preambleSize` items
+		for j := 0; j < preambleSize; j += 1 {
+			number := numbers[j+i]
+
+			// On every iteration check if the current value is present in indexes
+			for _, value := range indexes {
+				// If so, a pair is found
+				if value == number {
+					continue out
+				}
+			}
+
+			indexes = append(indexes, sum-number)
+		}
+
+		// When this is reached no sum was found
+		return sum
+	}
+
+	return -1
+}
+
+func Day09Part02(isTest bool) int {
+	// input := ReadInput("09", isTest)
+	// groups := strings.Split(input, "\n")
+
+	return -1
+}