feat: Implement 2017/day02 (#48)

* feat: 2017/day02 initial commit

* feat: Register 2017/day02

* chore: Add tests

* feat: Implement 2017/day02 part1

* feat: Implement 2017/day02 solution

* refactor: Fix code smells and linter bugs

cmd/aoc-cli/main_test.go

@@ -833,10 +833,10 @@ func testcases2017() []testcase {
 			want: puzzles.Result{
 				Year:  year,
 				Name:  puzzles.Day02.String(),
-				Part1: "",
-				Part2: "",
+				Part1: "32020",
+				Part2: "236",
 			},
-			wantErr: true,
+			wantErr: false,
 		},
 		{
 			name: "2017/day03",

internal/puzzles/input/data/2017/day02.txt

@@ -0,0 +1,16 @@
+116	1470	2610	179	2161	2690	831	1824	2361	1050	2201	118	145	2275	2625	2333
+976	220	1129	553	422	950	332	204	1247	1092	1091	159	174	182	984	713
+84	78	773	62	808	83	1125	1110	1184	145	1277	982	338	1182	75	679
+3413	3809	3525	2176	141	1045	2342	2183	157	3960	3084	2643	119	108	3366	2131
+1312	205	343	616	300	1098	870	1008	1140	1178	90	146	980	202	190	774
+4368	3905	3175	4532	3806	1579	4080	259	2542	221	4395	4464	208	3734	234	4225
+741	993	1184	285	1062	372	111	118	63	843	325	132	854	105	956	961
+85	79	84	2483	858	2209	2268	90	2233	1230	2533	322	338	68	2085	1267
+2688	2022	112	130	1185	103	1847	3059	911	107	2066	1788	2687	2633	415	1353
+76	169	141	58	161	66	65	225	60	152	62	64	156	199	80	56
+220	884	1890	597	3312	593	4259	222	113	2244	3798	4757	216	1127	4400	178
+653	369	216	132	276	102	265	889	987	236	239	807	1076	932	84	864
+799	739	75	1537	82	228	69	1397	1396	1203	1587	63	313	1718	1375	469
+1176	112	1407	136	1482	1534	1384	1202	604	851	190	284	1226	113	114	687
+73	1620	81	1137	812	75	1326	1355	1545	1666	1356	1681	1732	85	128	902
+571	547	160	237	256	30	496	592	385	576	183	692	192	387	647	233

internal/puzzles/solutions/2015/day01/solution_test.go

@@ -8,6 +8,24 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func Test_solution_Year(t *testing.T) {
+	var s solution
+
+	want := "2015"
+	got := s.Year()
+
+	assert.Equal(t, want, got)
+}
+
+func Test_solution_Day(t *testing.T) {
+	var s solution
+
+	want := "day01"
+	got := s.Day()
+
+	assert.Equal(t, want, got)
+}
+
 func Test_solution_Part1(t *testing.T) {
 	var s solution
 

internal/puzzles/solutions/2015/day02/solution_test.go

@@ -8,6 +8,24 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func Test_solution_Year(t *testing.T) {
+	var s solution
+
+	want := "2015"
+	got := s.Year()
+
+	assert.Equal(t, want, got)
+}
+
+func Test_solution_Day(t *testing.T) {
+	var s solution
+
+	want := "day02"
+	got := s.Day()
+
+	assert.Equal(t, want, got)
+}
+
 func Test_solution_Part1(t *testing.T) {
 	var s solution
 

internal/puzzles/solutions/2016/day01/solution_test.go

@@ -8,6 +8,24 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func Test_solution_Year(t *testing.T) {
+	var s solution
+
+	want := "2016"
+	got := s.Year()
+
+	assert.Equal(t, want, got)
+}
+
+func Test_solution_Day(t *testing.T) {
+	var s solution
+
+	want := "day01"
+	got := s.Day()
+
+	assert.Equal(t, want, got)
+}
+
 func Test_solution_Part1(t *testing.T) {
 	var s solution
 

internal/puzzles/solutions/2016/day02/solution_test.go

@@ -9,6 +9,24 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func Test_solution_Year(t *testing.T) {
+	var s solution
+
+	want := "2016"
+	got := s.Year()
+
+	assert.Equal(t, want, got)
+}
+
+func Test_solution_Day(t *testing.T) {
+	var s solution
+
+	want := "day02"
+	got := s.Day()
+
+	assert.Equal(t, want, got)
+}
+
 func Test_solution_Part1(t *testing.T) {
 	var s solution
 

internal/puzzles/solutions/2017/day01/solution_test.go

@@ -8,6 +8,24 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func Test_solution_Year(t *testing.T) {
+	var s solution
+
+	want := "2017"
+	got := s.Year()
+
+	assert.Equal(t, want, got)
+}
+
+func Test_solution_Day(t *testing.T) {
+	var s solution
+
+	want := "day01"
+	got := s.Day()
+
+	assert.Equal(t, want, got)
+}
+
 func Test_solution_Part1(t *testing.T) {
 	var s solution
 

internal/puzzles/solutions/2017/day02/solution.go

@@ -0,0 +1,130 @@
+// Package day02 contains solution for https://adventofcode.com/2017/day/2 puzzle.
+package day02
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+
+	"github.com/obalunenko/advent-of-code/internal/puzzles"
+)
+
+func init() {
+	puzzles.Register(solution{})
+}
+
+type solution struct{}
+
+func (s solution) Day() string {
+	return puzzles.Day02.String()
+}
+
+func (s solution) Year() string {
+	return puzzles.Year2017.String()
+}
+
+func (s solution) Part1(input io.Reader) (string, error) {
+	var f checksumFunc = func(row []string) (int, error) {
+		var min, max int
+
+		for i, number := range row {
+			d, err := strconv.Atoi(number)
+			if err != nil {
+				return 0, fmt.Errorf("atoi: %w", err)
+			}
+
+			if i == 0 {
+				min, max = d, d
+			}
+
+			if d < min {
+				min = d
+			}
+
+			if d > max {
+				max = d
+			}
+		}
+
+		return max - min, nil
+	}
+
+	return findChecksum(input, f)
+}
+
+func (s solution) Part2(input io.Reader) (string, error) {
+	var f checksumFunc = func(row []string) (int, error) {
+		numbers, err := stringsToNumbers(row)
+		if err != nil {
+			return 0, fmt.Errorf("strings to numbers: %w", err)
+		}
+
+		for i := 0; i < len(numbers); i++ {
+			d1 := numbers[i]
+
+			for j := i + 1; j < len(numbers); j++ {
+				d2 := numbers[j]
+
+				var a, b = d1, d2
+
+				if a < b {
+					a, b = b, a
+				}
+
+				if a%b == 0 {
+					return a / b, nil
+				}
+			}
+		}
+
+		return 0, ErrNotFound
+	}
+
+	return findChecksum(input, f)
+}
+
+func stringsToNumbers(row []string) ([]int, error) {
+	numbers := make([]int, 0, len(row))
+
+	for _, n := range row {
+		d, err := strconv.Atoi(n)
+		if err != nil {
+			return nil, fmt.Errorf("atoi: %w", err)
+		}
+
+		numbers = append(numbers, d)
+	}
+
+	return numbers, nil
+}
+
+// ErrNotFound returns when checksum could not be found.
+var ErrNotFound = errors.New("checksum not found")
+
+type checksumFunc func(row []string) (int, error)
+
+func findChecksum(spreadsheet io.Reader, f checksumFunc) (string, error) {
+	scanner := bufio.NewScanner(spreadsheet)
+
+	var checksum int
+
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		line = strings.ReplaceAll(line, "\t", " ")
+
+		numbers := strings.Split(line, " ")
+
+		n, err := f(numbers)
+		if err != nil {
+			return "", err
+		}
+
+		checksum += n
+	}
+
+	return strconv.Itoa(checksum), nil
+}

internal/puzzles/solutions/2017/day02/solution_test.go

@@ -0,0 +1,104 @@
+package day02
+
+import (
+	"io"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_solution_Year(t *testing.T) {
+	var s solution
+
+	want := "2017"
+	got := s.Year()
+
+	assert.Equal(t, want, got)
+}
+
+func Test_solution_Day(t *testing.T) {
+	var s solution
+
+	want := "day02"
+	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 bool
+	}{
+		{
+			name: "example from spec",
+			args: args{
+				input: strings.NewReader("5 1 9 5\n7 5 3\n2 4 6 8\n"),
+			},
+			want:    "18",
+			wantErr: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := s.Part1(tt.args.input)
+			if tt.wantErr {
+				require.Error(t, err)
+
+				return
+			}
+
+			require.NoError(t, err)
+			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 bool
+	}{
+		{
+			name: "example from spec",
+			args: args{
+				input: strings.NewReader("5 9 2 8\n9 4 7 3\n3 8 6 5\n"),
+			},
+			want:    "9",
+			wantErr: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := s.Part2(tt.args.input)
+			if tt.wantErr {
+				require.Error(t, err)
+
+				return
+			}
+
+			require.NoError(t, err)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}