days 1-5

03/main.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"bufio"
+	"log"
+	"os"
+	"sort"
+	"strconv"
+)
+
+const bitSize = 40
+
+func bitComplement(num uint64) uint64 {
+	return ^num & (1<<bitSize - 1)
+}
+
+func partOne(counts *[bitSize]int, total *int) (uint64, uint64) {
+	averageThreshold := *total / 2
+
+	var gammaRate uint64 = 0
+
+	for index, count := range counts {
+		if count > averageThreshold {
+			var add uint64 = 1 << (bitSize - 1 - index)
+			gammaRate += add
+		}
+	}
+
+	epsilonRate := bitComplement(gammaRate)
+	return gammaRate, epsilonRate
+}
+
+func reduce(slice []string, depth int, max bool) int64 {
+	var s []string
+	half := len(slice) / 2
+	if half == 0 {
+		ret, _ := strconv.ParseInt(slice[0], 2, 64)
+		return ret
+	}
+	maxDigit := slice[half][depth]
+
+	for _, str := range slice {
+		if max && str[depth] == maxDigit {
+			s = append(s, str)
+		}
+		if !max && str[depth] != maxDigit {
+			s = append(s, str)
+		}
+	}
+	return reduce(s, depth+1, max)
+}
+
+func partTwo(s []string) (int64, int64) {
+	sort.Strings(s)
+	return reduce(s, 0, true), reduce(s, 0, false)
+}
+
+func solve() {
+	file, err := os.Open("bigboi.txt")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	scanner.Split(bufio.ScanLines)
+
+	var counts [bitSize]int
+	var s []string
+
+	total := 0
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		for index, character := range line {
+			if character == '1' {
+				counts[index]++
+			}
+		}
+		s = append(s, line)
+		total++
+	}
+
+	partOne(&counts, &total)
+	//fmt.Println(int64(g) * int64(e))
+	partTwo(s)
+	//fmt.Println(o * c)
+}
+
+func main() {
+	solve()
+}