2024 Day 18 Part 1
This commit is contained in:
parent
9a389f5cfa
commit
7b16ef196e
1 changed files with 377 additions and 0 deletions
377
2024/src/day18.zig
Normal file
377
2024/src/day18.zig
Normal file
|
|
@ -0,0 +1,377 @@
|
|||
const std = @import("std");
|
||||
const aoc = @import("aoc.zig");
|
||||
|
||||
const Allocator = std.mem.Allocator;
|
||||
const List = std.ArrayList;
|
||||
const Map = std.AutoHashMap;
|
||||
const Set = aoc.AutoHashSet;
|
||||
const PriorityQueue = std.PriorityQueue;
|
||||
|
||||
pub fn main() !void {
|
||||
var gpa: std.heap.GeneralPurposeAllocator(.{}) = .{};
|
||||
defer _ = gpa.deinit();
|
||||
const allocator = gpa.allocator();
|
||||
|
||||
const text = try aoc.readAll(allocator, "input/day18.txt");
|
||||
defer allocator.free(text);
|
||||
|
||||
var bytes = try aoc.parseAll(Pos, allocator, text, "\n");
|
||||
defer bytes.deinit();
|
||||
|
||||
var grid = try Grid.init(allocator, Pos.new(70, 70));
|
||||
defer grid.deinit();
|
||||
|
||||
for (bytes.items[0..1024]) |pos| {
|
||||
try grid.put(pos, '#');
|
||||
}
|
||||
|
||||
var bw = std.io.bufferedWriter(std.io.getStdOut().writer());
|
||||
const stdout = bw.writer();
|
||||
|
||||
try stdout.print("{}\n", .{try search(allocator, grid, Pos.new(0, 0), grid.max)});
|
||||
try bw.flush();
|
||||
}
|
||||
|
||||
fn search(allocator: Allocator, grid: Grid, pos: Pos, _: Pos) !u64 {
|
||||
const start = State.new(pos);
|
||||
|
||||
const ctx = State.Context{
|
||||
.grid = grid,
|
||||
};
|
||||
|
||||
var exits = try SearchIterator(State).init(allocator, ctx, start);
|
||||
defer exits.deinit();
|
||||
|
||||
while (try exits.next(State.isGoal, State.heuristic)) |next| {
|
||||
return next.cost;
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
const State = struct {
|
||||
pos: Pos,
|
||||
|
||||
const Self = @This();
|
||||
|
||||
pub const Context = struct {
|
||||
grid: Grid,
|
||||
};
|
||||
|
||||
pub fn new(pos: Pos) Self {
|
||||
return Self{ .pos = pos };
|
||||
}
|
||||
|
||||
pub fn isInVoid(self: Self, ctx: Context) bool {
|
||||
const lo, const hi = .{ -1, 1 };
|
||||
|
||||
var dr: i32 = lo;
|
||||
while (dr <= hi) : (dr += 1) {
|
||||
var dc: i32 = lo;
|
||||
while (dc <= hi) : (dc += 1) {
|
||||
const d = Delta.new(dr, dc);
|
||||
if (!ctx.grid.passable(self.pos.add(d))) {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
}
|
||||
return true;
|
||||
}
|
||||
|
||||
pub fn isGoal(self: Self, ctx: Context) bool {
|
||||
return std.meta.eql(self.pos, ctx.grid.max);
|
||||
}
|
||||
|
||||
pub fn heuristic(self: Self, ctx: Context) u64 {
|
||||
return self.pos.distance(ctx.grid.max);
|
||||
}
|
||||
|
||||
pub const Neighbor = struct { Self, u64 };
|
||||
|
||||
pub fn neighbors(self: Self, allocator: Allocator, ctx: Context) !List(Neighbor) {
|
||||
var list = List(Neighbor).init(allocator);
|
||||
|
||||
for (self.pos.neighbors()) |next| {
|
||||
if (!ctx.grid.inBounds(next)) continue;
|
||||
if (ctx.grid.get(next) == '#') continue;
|
||||
|
||||
try list.append(Neighbor{ Self.new(next), 1 });
|
||||
}
|
||||
|
||||
return list;
|
||||
}
|
||||
};
|
||||
|
||||
const Pos = struct {
|
||||
r: i32,
|
||||
c: i32,
|
||||
|
||||
pub fn parse(_: Allocator, line: []const u8) !Pos {
|
||||
var nums = std.mem.splitScalar(u8, line, ',');
|
||||
const r = try std.fmt.parseInt(i32, nums.next().?, 10);
|
||||
const c = try std.fmt.parseInt(i32, nums.next().?, 10);
|
||||
return Pos{ .r = r, .c = c };
|
||||
}
|
||||
|
||||
fn new(r: i32, c: i32) Pos {
|
||||
return Pos{ .r = r, .c = c };
|
||||
}
|
||||
|
||||
fn add(self: Pos, d: Delta) Pos {
|
||||
return .{
|
||||
.r = self.r + d.dr,
|
||||
.c = self.c + d.dc,
|
||||
};
|
||||
}
|
||||
|
||||
fn move(self: Pos, dir: Direction) Pos {
|
||||
return self.add(dir.delta());
|
||||
}
|
||||
|
||||
fn neighbors(self: Pos) [4]Pos {
|
||||
return [4]Pos{
|
||||
self.add(Direction.n.delta()),
|
||||
self.add(Direction.e.delta()),
|
||||
self.add(Direction.s.delta()),
|
||||
self.add(Direction.w.delta()),
|
||||
};
|
||||
}
|
||||
|
||||
fn distance(self: Pos, other: Pos) u64 {
|
||||
var d: u64 = 0;
|
||||
d += @abs(self.r - other.r);
|
||||
d += @abs(self.c - other.c);
|
||||
return d;
|
||||
}
|
||||
|
||||
pub fn format(
|
||||
self: Pos,
|
||||
comptime _: []const u8,
|
||||
_: std.fmt.FormatOptions,
|
||||
writer: anytype,
|
||||
) !void {
|
||||
try writer.print("({d}, {d})", .{ self.r, self.c });
|
||||
}
|
||||
};
|
||||
|
||||
const Direction = enum {
|
||||
n,
|
||||
e,
|
||||
s,
|
||||
w,
|
||||
|
||||
fn delta(self: Direction) Delta {
|
||||
return switch (self) {
|
||||
.n => Delta.new(-1, 0),
|
||||
.s => Delta.new(1, 0),
|
||||
.w => Delta.new(0, -1),
|
||||
.e => Delta.new(0, 1),
|
||||
};
|
||||
}
|
||||
|
||||
fn clockwise(self: Direction) Direction {
|
||||
return switch (self) {
|
||||
.n => .e,
|
||||
.e => .s,
|
||||
.s => .w,
|
||||
.w => .n,
|
||||
};
|
||||
}
|
||||
|
||||
fn counterclockwise(self: Direction) Direction {
|
||||
return switch (self) {
|
||||
.n => .w,
|
||||
.w => .s,
|
||||
.s => .e,
|
||||
.e => .n,
|
||||
};
|
||||
}
|
||||
|
||||
pub fn format(
|
||||
self: Direction,
|
||||
comptime _: []const u8,
|
||||
_: std.fmt.FormatOptions,
|
||||
writer: anytype,
|
||||
) !void {
|
||||
const c: u8 = switch (self) {
|
||||
.n => 'N',
|
||||
.e => 'E',
|
||||
.s => 'S',
|
||||
.w => 'W',
|
||||
};
|
||||
try writer.print("{c}", .{c});
|
||||
}
|
||||
};
|
||||
|
||||
const Delta = struct {
|
||||
dr: i32,
|
||||
dc: i32,
|
||||
|
||||
fn new(dr: i32, dc: i32) Delta {
|
||||
return Delta{ .dr = dr, .dc = dc };
|
||||
}
|
||||
};
|
||||
|
||||
const Grid = struct {
|
||||
map: Map(Pos, u8),
|
||||
max: Pos,
|
||||
|
||||
fn init(allocator: Allocator, max: Pos) !Grid {
|
||||
return Grid{
|
||||
.map = Map(Pos, u8).init(allocator),
|
||||
.max = max,
|
||||
};
|
||||
}
|
||||
|
||||
fn deinit(self: *Grid) void {
|
||||
self.map.deinit();
|
||||
}
|
||||
|
||||
fn clone(self: Grid) !Grid {
|
||||
return Grid{
|
||||
.map = try self.map.clone(),
|
||||
.max = self.max,
|
||||
};
|
||||
}
|
||||
|
||||
fn iterator(self: *const Grid) Map(Pos, u8).Iterator {
|
||||
return self.map.iterator();
|
||||
}
|
||||
|
||||
fn get(self: *const Grid, pos: Pos) ?u8 {
|
||||
return self.map.get(pos);
|
||||
}
|
||||
|
||||
fn put(self: *Grid, pos: Pos, v: u8) !void {
|
||||
try self.map.put(pos, v);
|
||||
}
|
||||
|
||||
fn inBounds(self: Grid, pos: Pos) bool {
|
||||
return 0 <= pos.r and pos.r <= self.max.r and
|
||||
0 <= pos.c and pos.c <= self.max.c;
|
||||
}
|
||||
|
||||
fn passable(self: Grid, pos: Pos) bool {
|
||||
return self.inBounds(pos) and self.get(pos) != '#';
|
||||
}
|
||||
|
||||
pub fn format(
|
||||
self: Grid,
|
||||
comptime _: []const u8,
|
||||
_: std.fmt.FormatOptions,
|
||||
writer: anytype,
|
||||
) !void {
|
||||
var r: i32 = 0;
|
||||
while (r <= self.max.r) : (r += 1) {
|
||||
var c: i32 = 0;
|
||||
while (c <= self.max.c) : (c += 1) {
|
||||
if (self.get(Pos.new(r, c))) |x| {
|
||||
try writer.print("{c}", .{x});
|
||||
} else {
|
||||
try writer.print(" ", .{});
|
||||
}
|
||||
}
|
||||
try writer.print("|\n", .{});
|
||||
}
|
||||
}
|
||||
};
|
||||
|
||||
fn SearchIterator(comptime T: type) type {
|
||||
return struct {
|
||||
const Self = @This();
|
||||
|
||||
allocator: Allocator,
|
||||
ctx: T.Context,
|
||||
|
||||
queue: PriorityQueue(Entry, void, Entry.compare),
|
||||
dist: Map(T, u64),
|
||||
prev: Map(T, T),
|
||||
|
||||
const Entry = struct {
|
||||
state: T,
|
||||
cost: u64,
|
||||
heuristic: u64,
|
||||
|
||||
fn compare(_: void, a: Entry, b: Entry) std.math.Order {
|
||||
return std.math.order(a.cost + a.heuristic, b.cost + b.heuristic);
|
||||
}
|
||||
};
|
||||
|
||||
fn init(allocator: Allocator, ctx: T.Context, start: T) Allocator.Error!Self {
|
||||
var queue = PriorityQueue(Entry, void, comptime Entry.compare).init(allocator, {});
|
||||
|
||||
try queue.add(Entry{
|
||||
.state = start,
|
||||
.cost = 0,
|
||||
.heuristic = 0,
|
||||
});
|
||||
|
||||
var dist = Map(T, u64).init(allocator);
|
||||
try dist.put(start, 0);
|
||||
|
||||
const prev = Map(T, T).init(allocator);
|
||||
|
||||
return Self{
|
||||
.allocator = allocator,
|
||||
.queue = queue,
|
||||
.dist = dist,
|
||||
.prev = prev,
|
||||
.ctx = ctx,
|
||||
};
|
||||
}
|
||||
|
||||
fn deinit(self: *Self) void {
|
||||
self.prev.deinit();
|
||||
self.dist.deinit();
|
||||
self.queue.deinit();
|
||||
}
|
||||
|
||||
const GoalFn = fn (T, T.Context) bool;
|
||||
const HeuristicFn = fn (T, T.Context) u64;
|
||||
|
||||
const End = struct {
|
||||
state: T,
|
||||
cost: u64,
|
||||
};
|
||||
|
||||
pub fn next(self: *Self, isGoal: GoalFn, heuristic: HeuristicFn) !?End {
|
||||
while (self.queue.removeOrNull()) |entry| {
|
||||
const u, const cost = .{ entry.state, entry.cost };
|
||||
if (self.dist.get(u)) |best| {
|
||||
if (best < cost) {
|
||||
continue;
|
||||
}
|
||||
}
|
||||
|
||||
if (isGoal(u, self.ctx)) {
|
||||
return End{ .state = u, .cost = cost };
|
||||
}
|
||||
|
||||
var neighbors: List(T.Neighbor) = try u.neighbors(self.allocator, self.ctx);
|
||||
defer neighbors.deinit();
|
||||
|
||||
for (neighbors.items) |neighbor| {
|
||||
const v, const extra = neighbor;
|
||||
const alt = cost + extra;
|
||||
|
||||
if (self.dist.get(v)) |dv| {
|
||||
if (alt >= dv) {
|
||||
continue;
|
||||
}
|
||||
}
|
||||
|
||||
try self.prev.put(v, u);
|
||||
|
||||
try self.dist.put(v, alt);
|
||||
try self.queue.add(Entry{
|
||||
.state = v,
|
||||
.cost = alt,
|
||||
.heuristic = heuristic(v, self.ctx),
|
||||
});
|
||||
}
|
||||
}
|
||||
|
||||
return null;
|
||||
}
|
||||
};
|
||||
}
|
||||
Loading…
Reference in a new issue