Combine AoC Repos

2016/day04/main.go

@@ -0,0 +1,108 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+)
+
+const (
+	locChecksum = iota
+	locSector
+	locName
+)
+
+func main() {
+	input := stdinToStringSlice()
+	var sectorTotal int
+	for _, h := range input {
+		var chksum, sector, name string
+		var loc int
+		freq := make(map[rune]int)
+		for i := len(h) - 1; i >= 0; i-- {
+			switch h[i] {
+			case ']': // start reading checksum
+				loc = locChecksum
+			case '[': // start reading sector
+				loc = locSector
+			case '-':
+				if loc == locSector { // done with sector
+					loc = locName
+				}
+			default:
+				switch loc {
+				case locChecksum:
+					chksum = string(h[i]) + chksum
+				case locSector:
+					sector = string(h[i]) + sector
+				case locName:
+					name = string(h[i]) + name
+					freq[rune(h[i])]++
+				}
+			}
+		}
+		fmt.Println(decryptName(name, atoi(sector)), " :: ", sector)
+		var top rune
+		var realChecksum string
+		for i := 0; i < 5; i++ {
+			top, freq = findTop(freq)
+			realChecksum = realChecksum + string(top)
+		}
+		if realChecksum == chksum {
+			sectorTotal += atoi(sector)
+		}
+	}
+	fmt.Println("Sector Total: " + itoa(sectorTotal))
+
+}
+
+func decryptName(name string, rot int) string {
+	var decName string
+	for _, v := range name {
+		for k := 0; k < rot; k++ {
+			v++
+			if v == ('z' + 1) {
+				v = 'a'
+			}
+		}
+		decName = decName + string(v)
+	}
+	return decName
+}
+
+func findTop(inp map[rune]int) (rune, map[rune]int) {
+	var topCnt int
+	var topVal rune
+	for k, v := range inp {
+		if v > topCnt || (v == topCnt && k < topVal) {
+			topCnt = v
+			topVal = k
+		}
+	}
+	delete(inp, topVal)
+	return topVal, inp
+}
+
+func stdinToStringSlice() []string {
+	var input []string
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		input = append(input, scanner.Text())
+	}
+	return input
+}
+
+func itoa(i int) string {
+	return strconv.Itoa(i)
+}
+
+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
+}