Combine AoC Repos

2016/day16/main.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+)
+
+// Part 1 Disk Size: 272
+// Part 2 Disk Size: 35651584
+func main() {
+	diskSize := 272
+	if len(os.Args) > 1 {
+		switch os.Args[1] {
+		case "-2":
+			// Do part two
+			diskSize = 35651584
+		default:
+			// manually set disk size
+			diskSize = atoi(os.Args[1])
+		}
+	}
+	input := stdinToString()
+	for len(input) < diskSize {
+		input = dragonCurve(input)
+	}
+	input = input[:diskSize]
+	fmt.Println(checksum(input))
+}
+
+func dragonCurve(inp string) string {
+	return inp + "0" + invert(reverse(inp))
+}
+
+func invert(inp string) string {
+	var ret []rune
+	for i := range inp {
+		if inp[i] == '1' {
+			ret = append(ret, '0')
+		} else {
+			ret = append(ret, '1')
+		}
+	}
+	return string(ret)
+}
+
+func reverse(inp string) string {
+	var ret []byte
+	for i := len(inp) - 1; i >= 0; i-- {
+		ret = append(ret, inp[i])
+	}
+	return string(ret)
+}
+
+func checksum(inp string) string {
+	var chkSum []rune
+	for i := 0; i < len(inp); i += 2 {
+		if inp[i] == inp[i+1] {
+			chkSum = append(chkSum, '1')
+		} else {
+			chkSum = append(chkSum, '0')
+		}
+	}
+	if len(chkSum)%2 == 0 {
+		// Length is even, repeat
+		return checksum(string(chkSum))
+	}
+	return string(chkSum)
+}
+
+func stdinToString() string {
+	var input string
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		input += scanner.Text()
+	}
+	return input
+}
+
+func atoi(i string) int {
+	var ret int
+	var err error
+	if ret, err = strconv.Atoi(i); err != nil {
+		log.Fatal("Invalid Atoi")
+	}
+	return ret
+}