Day 7 part 1

day7/day7.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/jpastoor/advent-of-code-2016/aoc2016utils"
+)
+
+func main() {
+	loader := aoc2016utils.AssignmentLoader{}
+	input := loader.Load(7)
+
+	counter := 0
+	for _, line := range strings.Split(input, "\n") {
+		if checkTLSSupport(line) {
+			counter++
+		}
+	}
+
+	fmt.Println(counter)
+
+}
+
+func checkTLSSupport(ip string) bool {
+
+	// Split string in sequences
+	normal := []string{}
+	hypernet := []string{}
+
+	current := ""
+	for _, ch := range ip {
+		str := string(ch)
+
+		switch str {
+		case "[":
+			if current != "" {
+				normal = append(normal, current)
+				current = ""
+			}
+		case "]":
+			if current != "" {
+				hypernet = append(hypernet, current)
+				current = ""
+			}
+		default:
+			current += str
+		}
+	}
+
+	// Clean buffer at the end
+	if current != "" {
+		normal = append(normal, current)
+		current = ""
+	}
+
+	// Loop over all normal parts to see if there is an abba
+	normalContainsABBA := false
+	for _, input := range normal {
+		if containsABBA(input) {
+			normalContainsABBA = true
+			break
+		}
+	}
+
+	// Loop over all hypernet parts to see if there is an abba
+	hypernetContainsABBA := false
+	for _, input := range hypernet {
+		if containsABBA(input) {
+			hypernetContainsABBA = true
+			break
+		}
+	}
+
+	return normalContainsABBA && !hypernetContainsABBA
+}
+
+/**
+Check if string contains an ABBA
+*/
+func containsABBA(input string) bool {
+	// We loop over every char in groups of 4, changing 1 position at a time
+	for i := 0; i < len(input)-3; i++ {
+		// The ABBA check
+		if input[i] == input[i+3] && input[i+1] == input[i+2] && input[i+2] != input[i+3] {
+			return true
+		}
+	}
+
+	return false
+}

day7/day7_test.go

@@ -0,0 +1,38 @@
+package main
+
+import "testing"
+
+func TestTLSSupport(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  bool
+	}{
+		{
+			"abba outside square brackets",
+			"abba[mnop]qrst",
+			true,
+		},
+		{
+			"bddb is within square brackets, even though xyyx is outside square brackets",
+			"abcd[bddb]xyyx",
+			false,
+		},
+		{
+			"aaaa is invalid; the interior characters must be different",
+			"aaaa[qwer]tyui",
+			false,
+		},
+		{
+			"oxxo is outside square brackets, even though it's within a larger string",
+			"ioxxoj[asdfgh]zxcvbn",
+			true,
+		},
+	}
+
+	for _, tt := range tests {
+		if got := checkTLSSupport(tt.input); got != tt.want {
+			t.Errorf("%q. checkTLSSupport(%s) = %v, want %v", tt.name, tt.input, got, tt.want)
+		}
+	}
+}