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const std = @import("std");
const print = std.debug.print;
const assert = std.debug.assert;
const ArrayList = std.ArrayList;
const HashMap = std.HashMap;
const mem = std.mem;
const fin = mem.trim(u8, @embedFile("./input.txt"), &std.ascii.whitespace);
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
const allocator = gpa.allocator();
const Record = struct {
springs: []const u8,
arrangement: []const u64,
};
const State = struct {
i: u8,
j: u8,
streak: u8,
prev: u8,
pub fn print(self: @This(), springs: []const u8, arrangement: []const u64) void {
std.debug.print("streak = {d}, prev = {c} springs = '{s}' | ", .{ self.streak, self.prev, springs[self.i..] });
if (self.j <= arrangement.len) {
for (arrangement[self.j..]) |arr| {
std.debug.print("{d}, ", .{arr});
}
std.debug.print("\n", .{});
}
}
pub const ctx = struct {
pub fn hash(_: @This(), s: State) u64 {
return (@as(u32, s.i) << 24 | @as(u32, s.j) << 16 | @as(u32, s.prev) << 8 | s.streak);
}
pub fn eql(_: @This(), lhs: State, rhs: State) bool {
return lhs.i == rhs.i and
lhs.j == rhs.j and
lhs.prev == rhs.prev and
lhs.streak == rhs.streak;
}
};
};
const DPHashMap = HashMap(State, u64, State.ctx, 80);
fn evaluate(dp: *DPHashMap, springs: []const u8, arrangement: []const u64, state: State) u64 {
var ans: u64 = 0;
var prev = state.prev;
var streak = state.streak;
var j = state.j;
if (dp.get(state)) |val| {
return val;
}
defer {
dp.put(state, ans) catch unreachable;
}
if (j > arrangement.len or
j == arrangement.len and streak > 0 or
j < arrangement.len and streak > arrangement[j])
{
ans = 0;
return 0;
}
for (springs[state.i..], state.i..) |c, i| {
switch (c) {
'?' => {
// Assume current = '.'
const e1 = if (prev == '.')
evaluate(dp, springs, arrangement, State{
.i = @as(u8, @intCast(i)) + 1,
.j = j,
.streak = 0,
.prev = '.',
})
else if (j < arrangement.len and streak == arrangement[j])
evaluate(dp, springs, arrangement, State{
.i = @as(u8, @intCast(i)) + 1,
.j = j + 1,
.streak = 0,
.prev = '.',
})
else
0;
// Assume current = '#'
const e2 = evaluate(dp, springs, arrangement, State{
.i = @as(u8, @intCast(i)) + 1,
.j = j,
.streak = streak + 1,
.prev = '#',
});
ans = e1 + e2;
return ans;
},
'#' => {
streak += 1;
},
'.' => {
if (prev == '#') {
if (j < arrangement.len and streak != arrangement[j] or j >= arrangement.len) {
ans = 0;
return ans;
}
j += 1;
}
streak = 0;
},
else => unreachable,
}
prev = c;
}
ans = if (j >= arrangement.len and streak == 0 or
j == arrangement.len - 1 and streak == arrangement[j])
1
else
0;
return ans;
}
pub fn solve(records: []const Record) !void {
var part1: u64 = 0;
for (records) |record| {
const state = State{
.i = 0,
.j = 0,
.streak = 0,
.prev = '.',
};
var dp = DPHashMap.init(allocator);
const e = evaluate(&dp, record.springs, record.arrangement, state);
part1 += e;
}
print("{d}\n", .{part1});
var part2: u64 = 0;
for (records) |record| {
const unfolded_springs = try allocator.alloc(u8, record.springs.len * 5 + 4);
_ = try std.fmt.bufPrint(unfolded_springs, "{s}?{s}?{s}?{s}?{s}", .{
record.springs,
record.springs,
record.springs,
record.springs,
record.springs,
});
var unfolded_arrangement = ArrayList(u64).init(allocator);
for (0..5) |_| {
try unfolded_arrangement.appendSlice(record.arrangement);
}
const state = State{
.i = 0,
.j = 0,
.streak = 0,
.prev = '.',
};
var dp = DPHashMap.init(allocator);
const e = evaluate(&dp, unfolded_springs, unfolded_arrangement.items, state);
part2 += e;
}
print("{d}\n", .{part2});
}
pub fn main() !void {
var splitLines = mem.splitScalar(u8, fin, '\n');
var records = ArrayList(Record).init(allocator);
defer records.deinit();
while (splitLines.next()) |line| {
var toks = mem.tokenizeAny(u8, line, " ,");
const springs = toks.next().?;
var arrangement = ArrayList(u64).init(allocator);
while (toks.next()) |tok| {
try arrangement.append(try std.fmt.parseInt(u64, tok, 10));
}
try records.append(.{
.springs = springs,
.arrangement = arrangement.items,
});
}
try solve(records.items);
}
|
