Combine AoC Repos

2016/day14/main.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"crypto/md5"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+)
+
+var hashStore []string
+var salt string
+
+func main() {
+	if len(os.Args) < 3 {
+		fmt.Println("Usage: ./day14 <salt> <key-num>")
+		fmt.Println("  My input: ./day14 cuanljph 64")
+		os.Exit(1)
+	}
+	salt = os.Args[1]
+	keyNum := atoi(os.Args[2])
+	var foundKeys []string
+	tryIdx := 0
+	for len(foundKeys) < keyNum {
+		tst := getHash(tryIdx)
+		for i := range tst {
+			if len(tst) > i+3 {
+				if tst[i:i+3] == strings.Repeat(string(tst[i]), 3) {
+					// Found a triple, search the next 1000 for a quintuple
+					if searchForQuint(salt, tryIdx+1, string(tst[i])) {
+						foundKeys = append(foundKeys, tst)
+					}
+					// Once we test the first triplet, we're done with this one
+					break
+				}
+			}
+		}
+		tryIdx++
+	}
+	fmt.Println("Key:", getHash(tryIdx-1), "Idx:", tryIdx)
+}
+
+func getHash(idx int) string {
+	for len(hashStore)-1 < idx {
+		hashStore = append(
+			hashStore,
+			getStretchedHash(fmt.Sprintf("%x", md5.Sum([]byte(salt+itoa(len(hashStore)+1))))),
+		)
+	}
+	return hashStore[idx]
+}
+
+func getStretchedHash(s string) string {
+	for i := 0; i < 2016; i++ {
+		s = fmt.Sprintf("%x", md5.Sum([]byte(s)))
+	}
+	return s
+}
+
+func searchForQuint(salt string, startIdx int, srch string) bool {
+	for i := startIdx; i <= startIdx+1000; i++ {
+		tst := getHash(i)
+		if strings.Contains(tst, strings.Repeat(srch, 5)) {
+			return true
+		}
+	}
+	return false
+}
+
+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
+}
+
+func itoa(i int) string {
+	return strconv.Itoa(i)
+}