2015-day8: calculating encoded and decoded string lengths

2015/day08/main.go

@@ -0,0 +1,63 @@
+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 {
+	var codeChars, stringChars int
+	for _, line := range strings.Split(input, "\n") {
+		codeChars += len(line)
+
+		for i := 1; i < len(line)-1; i++ {
+			switch line[i] {
+			case '\\':
+				nextChar := line[i+1]
+				if nextChar == '\\' || nextChar == '"' {
+					i++ // skip an extra character
+				} else if nextChar == 'x' {
+					i += 3 // skip 2 extra chars
+				}
+			}
+			stringChars++
+		}
+	}
+
+	return codeChars - stringChars
+}
+
+func part2(input string) int {
+	var encodedLen, originalLen int
+	for _, line := range strings.Split(input, "\n") {
+		originalLen += len(line)
+		encodedLen += 2 // outer quotes
+		for i := 0; i < len(line); i++ {
+			switch line[i] {
+			case '"', '\\':
+				encodedLen += 2
+			default:
+				encodedLen++
+			}
+		}
+	}
+	return encodedLen - originalLen
+}

2015/day08/main_test.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/alexchao26/advent-of-code-go/util"
+)
+
+func Test_part1(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{"actual", util.ReadFile("input.txt"), 1371},
+	}
+	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)
+			}
+		})
+	}
+}
+
+func Test_part2(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  int
+	}{
+		{"actual", util.ReadFile("input.txt"), 2117},
+	}
+	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)
+			}
+		})
+	}
+}