2016-day7: more string validation stuff

2016/day07/main.go

@@ -0,0 +1,123 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strings"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func main() {
+	var part int
+	flag.IntVar(&part, "part", 1, "part 1 or 2")
+	flag.Parse()
+	fmt.Println("Running part", part)
+
+	var ans int
+	if part == 1 {
+		ans = part1(util.ReadFile("./input.txt"))
+	} else {
+		ans = part2(util.ReadFile("./input.txt"))
+	}
+	fmt.Println("Output:", ans)
+}
+
+func part1(input string) int {
+	insideBraces, outsideBraces := parseInput(input)
+
+	var count int
+	for i := range insideBraces {
+		inside, outside := insideBraces[i], outsideBraces[i]
+		var insidesHaveABBA bool
+		for _, str := range inside {
+			if hasABBA(str) {
+				insidesHaveABBA = true
+				break
+			}
+		}
+		if !insidesHaveABBA {
+			var outsidesHaveABBA bool
+			for _, str := range outside {
+				if hasABBA(str) {
+					outsidesHaveABBA = true
+				}
+			}
+			if outsidesHaveABBA {
+				count++
+			}
+		}
+	}
+
+	return count
+}
+
+func hasABBA(str string) bool {
+	for i := 3; i < len(str); i++ {
+		// match outsides, match insides, ensure insides and outsides are different
+		if str[i-3] == str[i] && str[i-2] == str[i-1] && str[i] != str[i-1] {
+			return true
+		}
+	}
+	return false
+}
+
+func part2(input string) int {
+	insideBraces, outsideBraces := parseInput(input)
+
+	var count int
+	for i := range insideBraces {
+		inside, outside := insideBraces[i], outsideBraces[i]
+
+		insideABAs := findABAs(inside)
+		outsideABAs := findABAs(outside)
+
+		for aba := range insideABAs {
+			// make new string in pattern BAB and see if it's in the outside hashmap
+			bab := fmt.Sprintf("%s%s%s", aba[1:2], aba[0:1], aba[1:2])
+			if outsideABAs[bab] {
+				count++
+				break
+			}
+		}
+	}
+
+	return count
+}
+
+func findABAs(strs []string) map[string]bool {
+	found := map[string]bool{}
+	for _, str := range strs {
+		for i := 2; i < len(str); i++ {
+			if str[i-2] == str[i] && str[i] != str[i-1] {
+				found[str[i-2:i+1]] = true
+			}
+		}
+	}
+	return found
+}
+
+func parseInput(input string) (insides, outsides [][]string) {
+	for _, line := range strings.Split(input, "\n") {
+		var collectChars string
+		var insideBraces, outsideBraces []string
+
+		// lazy, add an open bracket at the end to add the last collected string
+		// to the slice. A tricky input could've broken this logic
+		for _, rn := range line + "[" {
+			switch char := string(rn); char {
+			case "[":
+				outsideBraces = append(outsideBraces, collectChars)
+				collectChars = ""
+			case "]":
+				insideBraces = append(insideBraces, collectChars)
+				collectChars = ""
+			default:
+				collectChars += char
+			}
+		}
+		insides = append(insides, insideBraces)
+		outsides = append(outsides, outsideBraces)
+	}
+	return insides, outsides
+}

2016/day07/main_test.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+var example = `abba[mnop]qrst
+abcd[bddb]xyyx
+aaaa[qwer]tyui
+ioxxoj[asdfgh]zxcvbn`
+
+func Test_part1(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{"example", example, 2},
+		{"actual", util.ReadFile("input.txt"), 118},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part1(tt.input); got != tt.want {
+				t.Errorf("part1() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+var example2 = `aba[bab]xyz
+xyx[xyx]xyx
+aaa[kek]eke
+zazbz[bzb]cdb`
+
+func Test_part2(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{"example", example2, 3},
+		// {"actual", util.ReadFile("input.txt"), ACTUAL_ANSWER},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := part2(tt.input); got != tt.want {
+				t.Errorf("part2() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}