Day 4 part 1

main.go

@@ -10,8 +10,14 @@ func main() {
 	runAndBenchmark("01", "1", false, solutions.Day01Part01)
 	runAndBenchmark("01", "2", false, solutions.Day01Part02)
 
-	runAndBenchmark("02", "1", false, solutions.Day01Part01)
-	runAndBenchmark("02", "2", false, solutions.Day01Part02)
+	runAndBenchmark("02", "1", false, solutions.Day02Part01)
+	runAndBenchmark("02", "2", false, solutions.Day02Part02)
+
+	runAndBenchmark("03", "1", false, solutions.Day03Part01)
+	runAndBenchmark("03", "2", false, solutions.Day03Part02)
+
+	runAndBenchmark("04", "1", false, solutions.Day04Part01)
+	runAndBenchmark("04", "2", false, solutions.Day04Part02)
 }
 
 type execute func(bool) int
@@ -21,5 +27,5 @@ func runAndBenchmark(day, part string, isTest bool, fn execute) {
 	computation := fn(isTest)
 	endMs := time.Now().UnixMicro()
 	duration := endMs - startMs
-	fmt.Printf("Day %s part %s:\t%10d\t%5d micros.\n", day, part, computation, duration)
+	fmt.Printf("Day %s part %s:\t%12d\t%5d micros.\n", day, part, computation, duration)
 }

solutions/day03.go

@@ -0,0 +1,44 @@
+package solutions
+
+import "strings"
+
+func countTrees(input string, right, down int) int {
+	verticalPos := down
+	horizontalPos := right
+	lines := strings.Split(input, "\n")
+	width := len(lines[0])
+	treesCount := 0
+
+	for verticalPos < len(lines) {
+		line := lines[verticalPos]
+		charAt := string(line[horizontalPos])
+
+		if charAt == "#" {
+			treesCount += 1
+		}
+
+		horizontalPos += right
+		horizontalPos = horizontalPos % width
+		verticalPos += down
+	}
+
+	return treesCount
+}
+
+func Day03Part01(isTest bool) int {
+	input := ReadInput("03", isTest)
+
+	return countTrees(input, 3, 1)
+}
+
+func Day03Part02(isTest bool) int {
+	input := ReadInput("03", isTest)
+
+	amount1 := countTrees(input, 1, 1)
+	amount2 := countTrees(input, 3, 1)
+	amount3 := countTrees(input, 5, 1)
+	amount4 := countTrees(input, 7, 1)
+	amount5 := countTrees(input, 1, 2)
+
+	return amount1 * amount2 * amount3 * amount4 * amount5
+}

solutions/day04.go

@@ -0,0 +1,41 @@
+package solutions
+
+import (
+	"regexp"
+	"strings"
+)
+
+func Day04Part01(isTest bool) int {
+	input := ReadInput("04", isTest)
+	passports := strings.Split(input, "\n\n")
+
+	regex, _ := regexp.Compile("(\\w+:[\\w#]+)")
+
+	correctAmount := 0
+
+	for _, passport := range passports {
+		matches := regex.FindAllString(passport, -1)
+
+		values := make(map[string]string)
+
+		for _, match := range matches {
+			colonPosition := strings.Index(match, ":")
+			key := match[:colonPosition]
+			value := match[colonPosition+1:]
+			values[key] = value
+		}
+
+		_, cidMissing := values["cid"]
+		keysAmount := len(values)
+
+		if keysAmount == 8 || (keysAmount == 7 && !cidMissing) {
+			correctAmount += 1
+		}
+	}
+
+	return correctAmount
+}
+
+func Day04Part02(isTest bool) int {
+	return -1
+}