Day 7 Complete

day07/main.go

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+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"regexp"
+	"strings"
+)
+
+func main() {
+	ips := stdinToStringSlice()
+	var allowTLS []string
+	var allowSSL []string
+	for _, ip := range ips {
+		if hasTLS(ip) {
+			allowTLS = append(allowTLS, ip)
+		}
+		if hasSSL(ip) {
+			allowSSL = append(allowSSL, ip)
+		}
+	}
+	fmt.Println("IPs supporting TLS: ", len(allowTLS))
+	fmt.Println("IPs supporting SSL: ", len(allowSSL))
+}
+
+func hasTLS(ip string) bool {
+	bad := false
+	hprSq := getHypernetSqns(ip)
+	for _, hpr := range hprSq {
+		if hasABBA(hpr) {
+			return false
+		}
+	}
+	if !bad && hasABBA(ip) {
+		return true
+	}
+	return false
+}
+
+func hasSSL(ip string) bool {
+	hprSq := getHypernetSqns(ip)
+	rest := cutHypernetSqns(ip, hprSq)
+	for i := range rest {
+		if len(rest) > i+2 {
+			if rest[i] == rest[i+2] && rest[i] != rest[i+1] {
+				bab := string(rest[i+1]) + string(rest[i]) + string(rest[i+1])
+				for j := range hprSq {
+					if strings.Contains(hprSq[j], bab) {
+						return true
+					}
+				}
+			}
+		}
+	}
+	return false
+}
+
+func getHypernetSqns(ip string) []string {
+	var ret []string
+	re := regexp.MustCompile(`\[[^\[]*\]`)
+	s := re.FindAll([]byte(ip), -1)
+
+	for i := range s {
+		ret = append(ret, string(s[i][1:len(s[i])-1]))
+	}
+	return ret
+}
+
+func cutHypernetSqns(ip string, hpn []string) string {
+	for i := range hpn {
+		ip = strings.Replace(ip, hpn[i], "", -1)
+	}
+	return ip
+}
+
+func hasABBA(ip string) bool {
+	for j := range ip {
+		if len(ip) > j+3 {
+			if ip[j] == ip[j+3] && ip[j+1] == ip[j+2] && ip[j] != ip[j+1] {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func stdinToStringSlice() []string {
+	var input []string
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		input = append(input, scanner.Text())
+	}
+	return input
+}

day07/problem

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+Advent of Code
+
+--- Day 7: Internet Protocol Version 7 ---
+
+   While snooping around the local network of EBHQ, you compile a list of IP addresses (they're IPv7, of course; IPv6 is much too limited).
+   You'd like to figure out which IPs support TLS (transport-layer snooping).
+
+   An IP supports TLS if it has an Autonomous Bridge Bypass Annotation, or ABBA. An ABBA is any four-character sequence which consists of a
+   pair of two different characters followed by the reverse of that pair, such as xyyx or abba. However, the IP also must not have an ABBA
+   within any hypernet sequences, which are contained by square brackets.
+
+   For example:
+
+     • abba[mnop]qrst supports TLS (abba outside square brackets).
+     • abcd[bddb]xyyx does not support TLS (bddb is within square brackets, even though xyyx is outside square brackets).
+     • aaaa[qwer]tyui does not support TLS (aaaa is invalid; the interior characters must be different).
+     • ioxxoj[asdfgh]zxcvbn supports TLS (oxxo is outside square brackets, even though it's within a larger string).
+
+   How many IPs in your puzzle input support TLS?
+
+   Your puzzle answer was _____.
+
+--- Part Two ---
+
+   You would also like to know which IPs support SSL (super-secret listening).
+
+   An IP supports SSL if it has an Area-Broadcast Accessor, or ABA, anywhere in the supernet sequences (outside any square bracketed sections),
+   and a corresponding Byte Allocation Block, or BAB, anywhere in the hypernet sequences. An ABA is any three-character sequence which consists
+   of the same character twice with a different character between them, such as xyx or aba. A corresponding BAB is the same characters but in
+   reversed positions: yxy and bab, respectively.
+
+   For example:
+
+     • aba[bab]xyz supports SSL (aba outside square brackets with corresponding bab within square brackets).
+     • xyx[xyx]xyx does not support SSL (xyx, but no corresponding yxy).
+     • aaa[kek]eke supports SSL (eke in supernet with corresponding kek in hypernet; the aaa sequence is not related, because the interior
+       character must be different).
+     • zazbz[bzb]cdb supports SSL (zaz has no corresponding aza, but zbz has a corresponding bzb, even though zaz and zbz overlap).
+
+   How many IPs in your puzzle input support SSL?
+
+   Your puzzle answer was _______.
+
+References
+
+   Visible links
+   . http://adventofcode.com/
+   . http://adventofcode.com/2016/about
+   . http://adventofcode.com/2016/support
+   . http://adventofcode.com/2016/events
+   . http://adventofcode.com/2016/settings
+   . http://adventofcode.com/2016/auth/logout
+   . http://adventofcode.com/2016
+   . http://adventofcode.com/2016
+   . http://adventofcode.com/2016/leaderboard
+   . http://adventofcode.com/2016/stats
+   . http://adventofcode.com/2016/sponsors
+   . http://adventofcode.com/2016/sponsors
+   . https://en.wikipedia.org/wiki/IP_address
+   . https://en.wikipedia.org/wiki/IPv6
+   . http://adventofcode.com/2016
+   . http://adventofcode.com/2016/day/7/input