2017-day9: balanced parens with a twist

2017/day09/main.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+
+	"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)
+
+	ans := streamProcessing(util.ReadFile("./input.txt"), part)
+	util.CopyToClipboard(fmt.Sprintf("%v", ans))
+	fmt.Println("Output:", ans)
+}
+
+func streamProcessing(input string, part int) int {
+	var totalScore, garbageCount int
+
+	var inGarbage bool
+	var openCurlies int // equivalent to the current group's score
+
+	for i := 0; i < len(input); i++ {
+		char := string(input[i])
+		if inGarbage {
+			switch char {
+			case "!":
+				i++
+			case ">":
+				inGarbage = false
+			default:
+				garbageCount++ // part 2
+			}
+		} else {
+			switch char {
+			case "{":
+				openCurlies++
+			case "}":
+				totalScore += openCurlies // part 1
+				openCurlies--
+			case "<":
+				inGarbage = true
+			}
+		}
+	}
+
+	if part == 1 {
+		return totalScore
+	}
+	return garbageCount
+}

2017/day09/main_test.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func Test_streamProcessing(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		part  int
+		want  int
+	}{
+		{"part1_example 1", "{}", 1, 1},
+		{"part1_example 2", "{{}}", 1, 3},
+		{"part1_example 1", "{{}, {}}", 1, 5},
+		{"part1_example 1", "{{},<aksdljfsd!<> {}}", 1, 5},
+		{"part1_actual", util.ReadFile("input.txt"), 1, 16021},
+		{"part2_actual", util.ReadFile("input.txt"), 2, 7685},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := streamProcessing(tt.input, tt.part); got != tt.want {
+				t.Errorf("streamProcessing() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}