feat: Implement 2021/day08 puzzle

internal/puzzles/solutions/2021/day08/solution.go

@@ -0,0 +1,30 @@
+// Package day08 contains solution for https://adventofcode.com/2021/day/8 puzzle.
+package day08
+
+import (
+	"io"
+
+	"github.com/obalunenko/advent-of-code/internal/puzzles"
+)
+
+func init() {
+	puzzles.Register(solution{})
+}
+
+type solution struct{}
+
+func (solution) Day() string {
+	return puzzles.Day08.String()
+}
+
+func (solution) Year() string {
+	return puzzles.Year2021.String()
+}
+
+func (solution) Part1(input io.Reader) (string, error) {
+	return "", puzzles.ErrNotImplemented
+}
+
+func (solution) Part2(input io.Reader) (string, error) {
+	return "", puzzles.ErrNotImplemented
+}

internal/puzzles/solutions/2021/day08/solution_test.go

@@ -0,0 +1,117 @@
+package day08
+
+import (
+	"errors"
+	"io"
+	"path/filepath"
+	"testing"
+	"testing/iotest"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/obalunenko/advent-of-code/internal/puzzles/common/utils"
+)
+
+func Test_solution_Year(t *testing.T) {
+	var s solution
+
+	want := "2021"
+	got := s.Year()
+
+	assert.Equal(t, want, got)
+}
+
+func Test_solution_Day(t *testing.T) {
+	var s solution
+
+	want := "8"
+	got := s.Day()
+
+	assert.Equal(t, want, got)
+}
+
+func Test_solution_Part1(t *testing.T) {
+	var s solution
+
+	type args struct {
+		input io.Reader
+	}
+
+	tests := []struct {
+		name    string
+		args    args
+		want    string
+		wantErr assert.ErrorAssertionFunc
+	}{
+		{
+			name: "test example from description",
+			args: args{
+				input: utils.ReaderFromFile(t, filepath.Join("testdata", "input.txt")),
+			},
+			want:    "26",
+			wantErr: assert.NoError,
+		},
+		{
+			name: "",
+			args: args{
+				input: iotest.ErrReader(errors.New("custom error")),
+			},
+			want:    "",
+			wantErr: assert.Error,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := s.Part1(tt.args.input)
+			if !tt.wantErr(t, err) {
+				return
+			}
+
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+func Test_solution_Part2(t *testing.T) {
+	var s solution
+
+	type args struct {
+		input io.Reader
+	}
+
+	tests := []struct {
+		name    string
+		args    args
+		want    string
+		wantErr assert.ErrorAssertionFunc
+	}{
+		{
+			name: "test example from description",
+			args: args{
+				input: utils.ReaderFromFile(t, filepath.Join("testdata", "input.txt")),
+			},
+			want:    "",
+			wantErr: assert.NoError,
+		},
+		{
+			name: "",
+			args: args{
+				input: iotest.ErrReader(errors.New("custom error")),
+			},
+			want:    "",
+			wantErr: assert.Error,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := s.Part2(tt.args.input)
+			if !tt.wantErr(t, err) {
+				return
+			}
+
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}

internal/puzzles/solutions/2021/day08/spec.md

@@ -0,0 +1,90 @@
+# --- Day 8: Seven Segment Search ---
+
+## --- Part One ---
+
+You barely reach the safety of the cave when the whale smashes into the cave mouth, collapsing it. 
+Sensors indicate another exit to this cave at a much greater depth, so you have no choice but to press on.
+
+As your submarine slowly makes its way through the cave system, you notice that the four-digit seven-segment displays 
+in your submarine are malfunctioning; they must have been damaged during the escape. You'll be in a lot of trouble 
+without them, so you'd better figure out what's wrong.
+
+Each digit of a seven-segment display is rendered by turning on or off any of seven segments named a through g:
+
+```text
+  0:      1:      2:      3:      4:
+ aaaa    ....    aaaa    aaaa    ....
+b    c  .    c  .    c  .    c  b    c
+b    c  .    c  .    c  .    c  b    c
+ ....    ....    dddd    dddd    dddd
+e    f  .    f  e    .  .    f  .    f
+e    f  .    f  e    .  .    f  .    f
+ gggg    ....    gggg    gggg    ....
+
+  5:      6:      7:      8:      9:
+ aaaa    aaaa    aaaa    aaaa    aaaa
+b    .  b    .  .    c  b    c  b    c
+b    .  b    .  .    c  b    c  b    c
+ dddd    dddd    ....    dddd    dddd
+.    f  e    f  .    f  e    f  .    f
+.    f  e    f  .    f  e    f  .    f
+ gggg    gggg    ....    gggg    gggg
+```
+
+
+So, to render a 1, only segments c and f would be turned on; the rest would be off. To render a 7, only segments a, c, 
+and f would be turned on.
+
+The problem is that the signals which control the segments have been mixed up on each display. The submarine is still 
+trying to display numbers by producing output on signal wires a through g, but those wires are connected to segments 
+randomly. Worse, the wire/segment connections are mixed up separately for each four-digit display! 
+(All of the digits within a display use the same connections, though.)
+
+So, you might know that only signal wires b and g are turned on, but that doesn't mean segments b and g are turned on: 
+the only digit that uses two segments is 1, so it must mean segments c and f are meant to be on. With just that 
+information, you still can't tell which wire (b/g) goes to which segment (c/f). For that, you'll need to collect more 
+information.
+
+For each display, you watch the changing signals for a while, make a note of all ten unique signal patterns you see, 
+and then write down a single four digit output value (your puzzle input). 
+Using the signal patterns, you should be able to work out which pattern corresponds to which digit.
+
+### For example, here is what you might see in a single entry in your notes:
+
+```text
+acedgfb cdfbe gcdfa fbcad dab cefabd cdfgeb eafb cagedb ab |cdfeb fcadb cdfeb cdbaf
+```
+
+(The entry is wrapped here to two lines so it fits; in your notes, it will all be on a single line.)
+
+Each entry consists of ten unique signal patterns, a | delimiter, and finally the four digit output value. 
+Within an entry, the same wire/segment connections are used (but you don't know what the connections actually are). 
+The unique signal patterns correspond to the ten different ways the submarine tries to render a digit using the current 
+wire/segment connections. Because 7 is the only digit that uses three segments, dab in the above example means that to 
+render a 7, signal lines d, a, and b are on. Because 4 is the only digit that uses four segments, eafb means that to 
+render a 4, signal lines e, a, f, and b are on.
+
+Using this information, you should be able to work out which combination of signal wires corresponds to each of the ten 
+digits. Then, you can decode the four digit output value. Unfortunately, in the above example, 
+all of the digits in the output value (cdfeb fcadb cdfeb cdbaf) use five segments and are more difficult to deduce.
+
+### For now, focus on the easy digits. Consider this larger example:
+
+```text
+be cfbegad cbdgef fgaecd cgeb fdcge agebfd fecdb fabcd edb |fdgacbe cefdb cefbgd gcbe
+edbfga begcd cbg gc gcadebf fbgde acbgfd abcde gfcbed gfec |fcgedb cgb dgebacf gc
+fgaebd cg bdaec gdafb agbcfd gdcbef bgcad gfac gcb cdgabef |cg cg fdcagb cbg
+fbegcd cbd adcefb dageb afcb bc aefdc ecdab fgdeca fcdbega |efabcd cedba gadfec cb
+aecbfdg fbg gf bafeg dbefa fcge gcbea fcaegb dgceab fcbdga |gecf egdcabf bgf bfgea
+fgeab ca afcebg bdacfeg cfaedg gcfdb baec bfadeg bafgc acf |gebdcfa ecba ca fadegcb
+dbcfg fgd bdegcaf fgec aegbdf ecdfab fbedc dacgb gdcebf gf |cefg dcbef fcge gbcadfe
+bdfegc cbegaf gecbf dfcage bdacg ed bedf ced adcbefg gebcd |ed bcgafe cdgba cbgef
+egadfb cdbfeg cegd fecab cgb gbdefca cg fgcdab egfdb bfceg |gbdfcae bgc cg cgb
+gcafb gcf dcaebfg ecagb gf abcdeg gaef cafbge fdbac fegbdc |fgae cfgab fg bagce
+```
+
+Because the digits 1, 4, 7, and 8 each use a unique number of segments, you should be able to tell which combinations 
+of signals correspond to those digits. Counting only digits in the output values (the part after | on each line), 
+in the above example, there are 26 instances of digits that use a unique number of segments (highlighted above).
+
+In the output values, how many times do digits 1, 4, 7, or 8 appear?

internal/puzzles/solutions/2021/day08/testdata/input.txt

@@ -0,0 +1,10 @@
+be cfbegad cbdgef fgaecd cgeb fdcge agebfd fecdb fabcd edb |fdgacbe cefdb cefbgd gcbe
+edbfga begcd cbg gc gcadebf fbgde acbgfd abcde gfcbed gfec |fcgedb cgb dgebacf gc
+fgaebd cg bdaec gdafb agbcfd gdcbef bgcad gfac gcb cdgabef |cg cg fdcagb cbg
+fbegcd cbd adcefb dageb afcb bc aefdc ecdab fgdeca fcdbega |efabcd cedba gadfec cb
+aecbfdg fbg gf bafeg dbefa fcge gcbea fcaegb dgceab fcbdga |gecf egdcabf bgf bfgea
+fgeab ca afcebg bdacfeg cfaedg gcfdb baec bfadeg bafgc acf |gebdcfa ecba ca fadegcb
+dbcfg fgd bdegcaf fgec aegbdf ecdfab fbedc dacgb gdcebf gf |cefg dcbef fcge gbcadfe
+bdfegc cbegaf gecbf dfcage bdacg ed bedf ced adcbefg gebcd |ed bcgafe cdgba cbgef
+egadfb cdbfeg cegd fecab cgb gbdefca cg fgcdab egfdb bfceg |gbdfcae bgc cg cgb
+gcafb gcf dcaebfg ecagb gf abcdeg gaef cafbge fdbac fegbdc |fgae cfgab fg bagce

internal/puzzles/solutions/register_2021.go

@@ -18,4 +18,6 @@ import (
 	_ "github.com/obalunenko/advent-of-code/internal/puzzles/solutions/2021/day06"
 	// register day07 solution.
 	_ "github.com/obalunenko/advent-of-code/internal/puzzles/solutions/2021/day07"
+	// register day08 solution.
+	_ "github.com/obalunenko/advent-of-code/internal/puzzles/solutions/2021/day08"
 )