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| 1 | +// Package day02 contains solution for https://adventofcode.com/2016/day/2 puzzle. |
| 2 | +package day02 |
| 3 | + |
| 4 | +import ( |
| 5 | + "bufio" |
| 6 | + "errors" |
| 7 | + "fmt" |
| 8 | + "io" |
| 9 | + "strings" |
| 10 | + |
| 11 | + "github.com/obalunenko/advent-of-code/internal/puzzles" |
| 12 | +) |
| 13 | + |
| 14 | +func init() { |
| 15 | + puzzles.Register(solution{}) |
| 16 | +} |
| 17 | + |
| 18 | +type solution struct{} |
| 19 | + |
| 20 | +func (s solution) Day() string { |
| 21 | + return puzzles.Day02.String() |
| 22 | +} |
| 23 | + |
| 24 | +func (s solution) Year() string { |
| 25 | + return puzzles.Year2016.String() |
| 26 | +} |
| 27 | + |
| 28 | +func (s solution) Part1(input io.Reader) (string, error) { |
| 29 | + return part1(input) |
| 30 | +} |
| 31 | + |
| 32 | +func (s solution) Part2(input io.Reader) (string, error) { |
| 33 | + return part2(input) |
| 34 | +} |
| 35 | + |
| 36 | +func part2(input io.Reader) (string, error) { |
| 37 | + kpd := loadKeypadPart2() |
| 38 | + |
| 39 | + return getPassword(kpd, input) |
| 40 | +} |
| 41 | + |
| 42 | +func part1(input io.Reader) (string, error) { |
| 43 | + kpd := loadKeypadPart1() |
| 44 | + |
| 45 | + return getPassword(kpd, input) |
| 46 | +} |
| 47 | + |
| 48 | +func getPassword(kpd keypad, input io.Reader) (string, error) { |
| 49 | + reader := bufio.NewReader(input) |
| 50 | + |
| 51 | + var pwd strings.Builder |
| 52 | + |
| 53 | + for { |
| 54 | + r, _, err := reader.ReadRune() |
| 55 | + if err != nil { |
| 56 | + if errors.Is(err, io.EOF) { |
| 57 | + break |
| 58 | + } |
| 59 | + |
| 60 | + return "", fmt.Errorf("read rune: %w", err) |
| 61 | + } |
| 62 | + |
| 63 | + m := string(r) |
| 64 | + |
| 65 | + if r == '\n' { |
| 66 | + cur := kpd.numb() |
| 67 | + |
| 68 | + _, err = pwd.WriteString(cur) |
| 69 | + if err != nil { |
| 70 | + return "", fmt.Errorf("write string: %w", err) |
| 71 | + } |
| 72 | + |
| 73 | + continue |
| 74 | + } |
| 75 | + |
| 76 | + if err = kpd.move(move(m)); err != nil { |
| 77 | + return "", fmt.Errorf("move: %w", err) |
| 78 | + } |
| 79 | + } |
| 80 | + |
| 81 | + return pwd.String(), nil |
| 82 | +} |
| 83 | + |
| 84 | +type move string |
| 85 | + |
| 86 | +const ( |
| 87 | + up = move("U") |
| 88 | + down = move("D") |
| 89 | + left = move("L") |
| 90 | + right = move("R") |
| 91 | +) |
| 92 | + |
| 93 | +type keypadPos struct { |
| 94 | + x int |
| 95 | + y int |
| 96 | +} |
| 97 | + |
| 98 | +type grid [][]string |
| 99 | + |
| 100 | +type keypad struct { |
| 101 | + finger keypadPos |
| 102 | + grid grid |
| 103 | +} |
| 104 | + |
| 105 | +/* |
| 106 | +loadKeypadPart2 |
| 107 | +keyboard |
| 108 | +
|
| 109 | + 1 |
| 110 | + 2 3 4 |
| 111 | + 5 6 7 8 9 |
| 112 | + A B C |
| 113 | + D |
| 114 | +
|
| 115 | +start at `5` |
| 116 | +
|
| 117 | +let's predict that this is a 2 dimension matrix and '5' is 0,2m |
| 118 | +*/ |
| 119 | +func loadKeypadPart2() keypad { |
| 120 | + start := keypadPos{ |
| 121 | + x: 0, |
| 122 | + y: 2, |
| 123 | + } |
| 124 | + |
| 125 | + g := [][]string{ |
| 126 | + {"", "", "1", "", ""}, |
| 127 | + {"", "2", "3", "4", ""}, |
| 128 | + {"5", "6", "7", "8", "9"}, |
| 129 | + {"", "A", "B", "C", ""}, |
| 130 | + {"", "", "D", "", ""}, |
| 131 | + } |
| 132 | + |
| 133 | + return keypad{ |
| 134 | + finger: start, |
| 135 | + grid: g, |
| 136 | + } |
| 137 | +} |
| 138 | + |
| 139 | +/* |
| 140 | +loadKeypadPart1 |
| 141 | +keyboard |
| 142 | + 1 2 3 |
| 143 | + 4 5 6 |
| 144 | + 7 8 9 |
| 145 | +
|
| 146 | +let's predict that this is a 2 dimension matrix and 5 is a 1,1 |
| 147 | +*/ |
| 148 | +func loadKeypadPart1() keypad { |
| 149 | + g := [][]string{ |
| 150 | + {"1", "2", "3"}, |
| 151 | + {"4", "5", "6"}, |
| 152 | + {"7", "8", "9"}, |
| 153 | + } |
| 154 | + |
| 155 | + start := keypadPos{ |
| 156 | + x: 1, |
| 157 | + y: 1, |
| 158 | + } |
| 159 | + |
| 160 | + return newKeypad(g, start) |
| 161 | +} |
| 162 | + |
| 163 | +func newKeypad(specs grid, startPos keypadPos) keypad { |
| 164 | + return keypad{ |
| 165 | + finger: startPos, |
| 166 | + grid: specs, |
| 167 | + } |
| 168 | +} |
| 169 | + |
| 170 | +func (k *keypad) move(m move) error { |
| 171 | + switch m { |
| 172 | + case up: |
| 173 | + if k.canMoveUp() { |
| 174 | + k.finger.y-- |
| 175 | + } |
| 176 | + |
| 177 | + case down: |
| 178 | + if k.canMoveDown() { |
| 179 | + k.finger.y++ |
| 180 | + } |
| 181 | + |
| 182 | + case left: |
| 183 | + if k.canMoveLeft() { |
| 184 | + k.finger.x-- |
| 185 | + } |
| 186 | + case right: |
| 187 | + if k.canMoveRight() { |
| 188 | + k.finger.x++ |
| 189 | + } |
| 190 | + default: |
| 191 | + return fmt.Errorf("unsupported move") |
| 192 | + } |
| 193 | + |
| 194 | + return nil |
| 195 | +} |
| 196 | + |
| 197 | +func (k keypad) canMoveRight() bool { |
| 198 | + cur := k.finger |
| 199 | + |
| 200 | + if cur.x == len(k.grid[cur.y])-1 { |
| 201 | + return false |
| 202 | + } |
| 203 | + |
| 204 | + return k.grid[cur.y][cur.x+1] != "" |
| 205 | +} |
| 206 | + |
| 207 | +func (k keypad) canMoveLeft() bool { |
| 208 | + cur := k.finger |
| 209 | + |
| 210 | + if cur.x == 0 { |
| 211 | + return false |
| 212 | + } |
| 213 | + |
| 214 | + return k.grid[cur.y][cur.x-1] != "" |
| 215 | +} |
| 216 | + |
| 217 | +func (k keypad) canMoveUp() bool { |
| 218 | + cur := k.finger |
| 219 | + |
| 220 | + if cur.y == 0 { |
| 221 | + return false |
| 222 | + } |
| 223 | + |
| 224 | + return k.grid[cur.y-1][cur.x] != "" |
| 225 | +} |
| 226 | + |
| 227 | +func (k keypad) canMoveDown() bool { |
| 228 | + cur := k.finger |
| 229 | + |
| 230 | + if cur.y == len(k.grid)-1 { |
| 231 | + return false |
| 232 | + } |
| 233 | + |
| 234 | + return k.grid[cur.y+1][cur.x] != "" |
| 235 | +} |
| 236 | + |
| 237 | +func (k keypad) numb() string { |
| 238 | + return k.grid[k.finger.y][k.finger.x] |
| 239 | +} |
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