68 lines
1.9 KiB
Zig
68 lines
1.9 KiB
Zig
const std = @import("std");
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const common = @import("common.zig");
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const alloc = std.heap.page_allocator;
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const List = std.ArrayList;
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const HashMap = std.AutoHashMap(usize, u8);
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const data = @embedFile("inputs/puzzle.txt");
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pub fn main() !void {
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const stdout = std.io.getStdOut().writer();
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const cards = try common.parse(data);
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defer cards.deinit();
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const last_card_id = cards.items.len - 1;
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var matches = HashMap.init(alloc);
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defer matches.deinit();
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var card_stack = List(usize).init(alloc);
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defer card_stack.deinit();
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{
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var card_id = cards.items.len;
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var cards_iter = std.mem.reverseIterator(cards.items);
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while (cards_iter.next()) |card| {
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card_id -= 1;
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try matches.put(card_id, 0);
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try card_stack.append(card_id);
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for (card.winning.items) |winning_num| {
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for (card.having.items) |having_num| {
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if (winning_num == having_num) {
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if (matches.get(card_id)) |match| {
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try matches.put(card_id, match + 1);
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}
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}
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}
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}
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}
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}
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var total_cards: u32 = 0;
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while (card_stack.popOrNull()) |card_id| {
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total_cards += 1;
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const card_matches = matches.get(card_id).?;
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if (card_matches != 0 and card_id < last_card_id) {
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const remaining_cards = last_card_id - card_id;
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if (remaining_cards > 0) {
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const remaining_matches = if (remaining_cards >= card_matches) card_matches else remaining_cards;
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const new_cards_start = card_id + 1;
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const new_cards_end = card_id + remaining_matches + 1;
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for (new_cards_start..new_cards_end) |new_card_id| {
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try card_stack.append(new_card_id);
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}
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}
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}
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}
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try stdout.print("{d}\n", .{total_cards});
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}
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