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day 23
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+115
-48
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2 files changed

+115
-48
lines changed

‎.vscode/launch.json

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@
1212
"preLaunchTask": "build",
1313
// If you have changed target frameworks, make sure to update the program path.
1414
"program": "${workspaceFolder}/bin/Debug/net6.0/adventofcode.dll",
15-
"args": ["today"],
15+
"args": ["2021/23"],
1616
"cwd": "${workspaceFolder}",
1717
// For more information about the 'console' field, see https://github.com/OmniSharp/omnisharp-vscode/blob/master/debugger-launchjson.md#console-terminal-window
1818
"console": "internalConsole",

‎2021/Day23/Solution.cs

Lines changed: 114 additions & 47 deletions
Original file line numberDiff line numberDiff line change
@@ -8,23 +8,24 @@ namespace AdventOfCode.Y2021.Day23;
88
[ProblemName("Amphipod")]
99
class Solution : Solver {
1010

11-
public object PartOne(string input) => Solve(input).Min();
12-
public object PartTwo(string input) => Solve(Upscale(input)).Min();
11+
public object PartOne(string input) => Solve(input);
12+
public object PartTwo(string input) => Solve(Upscale(input));
1313

14-
string Upscale(string input){
14+
string Upscale(string input) {
1515
var lines = input.Split("\n").ToList();
1616
lines.Insert(3, " #D#C#B#A#");
1717
lines.Insert(4, " #D#B#A#C#");
1818
return string.Join("\n", lines);
1919
}
2020

21-
IEnumerable<int> Solve(string input) {
21+
int Solve(string input) {
2222
var maze = GetMaze(input);
2323

2424
var q = new PriorityQueue<Maze, int>();
25-
var seen = new Dictionary<string, Maze>();
26-
q.Enqueue(maze, maze.cost);
27-
seen.Add(maze.Tsto(), maze);
25+
var cost = new Dictionary<Maze, int>();
26+
27+
q.Enqueue(maze, 0);
28+
cost.Add(maze, 0);
2829

2930
bool finished(Maze maze) {
3031
bool colMatch(int icol, char c) {
@@ -39,28 +40,36 @@ bool colMatch(int icol, char c) {
3940
}
4041

4142
while (q.Count > 0) {
42-
maze = q.Dequeue();
43-
44-
foreach (var mazeT in Neighbours(maze)) {
45-
if (finished(mazeT)) {
46-
yield return mazeT.cost;
47-
} else if (!seen.ContainsKey(mazeT.Tsto()) || seen[mazeT.Tsto()].cost > mazeT.cost) {
48-
seen[mazeT.Tsto()] = mazeT;
49-
q.Enqueue(mazeT with { prev = maze }, mazeT.cost);
43+
while (cost[q.UnorderedItems.First().Element] != q.UnorderedItems.First().Priority) {
44+
q.Dequeue();
45+
}
46+
47+
maze = q.Dequeue();;
48+
49+
if (finished(maze)) {
50+
return cost[maze];
51+
}
52+
53+
foreach (var n in Neighbours(maze)) {
54+
if (n.cost + cost[maze] < cost.GetValueOrDefault(n.maze, int.MaxValue)) {
55+
cost[n.maze] = n.cost + cost[maze];
56+
q.Enqueue(n.maze, cost[n.maze]);
5057
}
5158
}
5259
}
60+
61+
throw new Exception();
5362
}
5463

5564
Maze GetMaze(string input) {
5665
var map = input.Split("\n");
57-
return new Maze((
58-
from y in Enumerable.Range(0, map.Length)
59-
from x in Enumerable.Range(0, map[0].Length)
60-
select new KeyValuePair<Point, char>(new Point(y, x), y < map.Length && x < map[y].Length ? map[y][x] : ' ')
61-
).ToImmutableDictionary(),
62-
0
63-
);
66+
var maze = new Maze(0, 0, 0, 0, map.Length > 6);
67+
foreach (var y in Enumerable.Range(0, map.Length)) {
68+
foreach (var x in Enumerable.Range(0, map[0].Length)) {
69+
maze = maze.SetItem(new Point(y, x), y < map.Length && x < map[y].Length ? map[y][x] : '#');
70+
}
71+
}
72+
return maze;
6473
}
6574

6675
int stepCost(char actor) {
@@ -97,7 +106,7 @@ bool finishedColumn(Maze maze, int icol) {
97106
return true;
98107
}
99108

100-
IEnumerable<Maze> Neighbours(Maze maze) {
109+
IEnumerable<(Maze maze, int cost)> Neighbours(Maze maze) {
101110

102111
bool columnIsClean(int icol, char ch) {
103112
var pt = new Point(2, icol);
@@ -125,7 +134,7 @@ Point step(Point pt) {
125134
}
126135

127136
// le-e lehet menni?
128-
Maze Lemegy(Maze maze) {
137+
(Maze maze, int cost) Lemegy(Maze maze) {
129138
for (var icol = 1; icol < 12; icol++) {
130139
var ch = maze.ItemAt(new Point(1, icol));
131140

@@ -144,17 +153,16 @@ Maze Lemegy(Maze maze) {
144153
steps++;
145154
}
146155

147-
return Lemegy(maze with {
148-
map = maze.map.SetItem(new Point(1, icol), '.').SetItem(pt, ch),
149-
cost = maze.cost + steps * stepCost(ch)
150-
});
156+
var l = Lemegy(maze.SetItem(new Point(1, icol), '.').SetItem(pt, ch));
157+
return (l.maze, l.cost + steps * stepCost(ch));
151158
}
152159
}
153-
return maze;
160+
return (maze, 0);
154161
}
155162

156-
if (Lemegy(maze).Tsto() != maze.Tsto()) {
157-
yield return Lemegy(maze);
163+
var lemegy = Lemegy(maze);
164+
if (lemegy.cost != 0) {
165+
yield return lemegy;
158166
yield break;
159167
}
160168
var allowedHColumns = new int[] { 1, 2, 4, 6, 8, 10, 11 };
@@ -184,10 +192,10 @@ Maze Lemegy(Maze maze) {
184192
while (maze.ItemAt(ptDst) == '.') {
185193

186194
if (allowedHColumns.Contains(ptDst.icol)) {
187-
yield return maze with {
188-
map = maze.map.SetItem(ptSrc, '.').SetItem(ptDst, ch),
189-
cost = maze.cost + (stepsV + stepsH) * stepCost(ch)
190-
};
195+
yield return (
196+
maze.SetItem(ptSrc, '.').SetItem(ptDst, ch),
197+
(stepsV + stepsH) * stepCost(ch)
198+
);
191199
}
192200

193201
if (dj == -1) {
@@ -209,19 +217,78 @@ record Point(int irow, int icol) {
209217
public Point Left => new Point(irow, icol - 1);
210218
public Point Right => new Point(irow, icol + 1);
211219
}
212-
record Maze(ImmutableDictionary<Point, char> map, int cost, Maze prev = null) {
213-
214-
public char ItemAt(Point pt) => map.GetValueOrDefault(pt, '#');
220+
record Maze(int a, int b, int c, int d, bool big) {
221+
222+
int BitFromPoint(Point pt) =>
223+
(big, pt.irow, pt.icol) switch {
224+
(_, 1, 1) => 1 << 0,
225+
(_, 1, 2) => 1 << 1,
226+
(_, 1, 3) => 1 << 2,
227+
(_, 1, 4) => 1 << 3,
228+
(_, 1, 5) => 1 << 4,
229+
(_, 1, 6) => 1 << 5,
230+
(_, 1, 7) => 1 << 6,
231+
(_, 1, 8) => 1 << 7,
232+
(_, 1, 9) => 1 << 8,
233+
(_, 1, 10) => 1 << 9,
234+
(_, 1, 11) => 1 << 10,
235+
236+
(_, 2, 3) => 1 << 11,
237+
(_, 2, 5) => 1 << 12,
238+
(_, 2, 7) => 1 << 13,
239+
(_, 2, 9) => 1 << 14,
240+
241+
(_, 3, 3) => 1 << 15,
242+
(_, 3, 5) => 1 << 16,
243+
(_, 3, 7) => 1 << 17,
244+
(_, 3, 9) => 1 << 18,
245+
246+
(true, 4, 3) => 1 << 19,
247+
(true, 4, 5) => 1 << 20,
248+
(true, 4, 7) => 1 << 21,
249+
(true, 4, 9) => 1 << 22,
250+
251+
(true, 5, 3) => 1 << 23,
252+
(true, 5, 5) => 1 << 24,
253+
(true, 5, 7) => 1 << 25,
254+
(true, 5, 9) => 1 << 26,
255+
256+
_ => 1 << 31,
257+
};
258+
259+
public char ItemAt(Point pt) {
260+
var bit = BitFromPoint(pt);
261+
return
262+
bit == 1 << 31 ? '#' :
263+
(a & bit) != 0 ? 'A' :
264+
(b & bit) != 0 ? 'B' :
265+
(c & bit) != 0 ? 'C' :
266+
(d & bit) != 0 ? 'D' :
267+
(d & bit) != 0 ? 'D' :
268+
'.';
269+
}
215270

216-
public string Tsto() {
217-
var st = "";
218-
for (var irow = 0; irow < 7; irow++) {
219-
for (var icol = 0; icol < 13; icol++) {
220-
st += map.GetValueOrDefault(new Point(irow, icol), ' ');
221-
}
222-
st += "\n";
271+
public Maze SetItem(Point pt, char ch) {
272+
var bit = BitFromPoint(pt);
273+
if (bit == 1 << 31) {
274+
if (ch != '#' && ch != ' ')
275+
throw new Exception();
276+
return this;
223277
}
224-
st += "---\n";
225-
return st;
278+
279+
return ch switch {
280+
'.' =>
281+
this with {
282+
a = a & ~bit,
283+
b = b & ~bit,
284+
c = c & ~bit,
285+
d = d & ~bit
286+
},
287+
'A' => this with { a = a | bit },
288+
'B' => this with { b = b | bit },
289+
'C' => this with { c = c | bit },
290+
'D' => this with { d = d | bit },
291+
_ => throw new Exception()
292+
};
226293
}
227294
}

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