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91 lines
2.5 KiB
Zig
91 lines
2.5 KiB
Zig
const std = @import("std");
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const Card = struct { winning: std.ArrayList(u8), have: std.ArrayList(u8), copies: u64 };
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pub fn main() !void {
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const content = @embedFile("data.txt");
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var cards = try parseCards(content);
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defer cards.deinit();
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var score1 = try findScore(&cards, 1);
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std.debug.print("part 1: {d}\n", .{score1});
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_ = try findScore(&cards, 2);
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var numCards: u128 = 0;
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for (cards.items) |c| {
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numCards += c.copies;
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}
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std.debug.print("part 2: {any}\n", .{numCards});
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}
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fn findScore(cards: *std.ArrayList(Card), part: u8) !u64 {
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var total: u64 = 0;
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// iterate over all cards
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for (cards.items, 0..) |card, i| {
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var numWinners: usize = 0;
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var score: u32 = 0;
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// iterate over the numbers we have
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for (card.have.items) |n| {
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// and the winning numbers
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for (card.winning.items) |w| {
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if (n == w) {
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numWinners += 1;
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score = if (score == 0) 1 else score * 2;
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}
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}
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}
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if (part == 2) {
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for (0..numWinners) |j| {
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cards.items[i + j + 1].copies += card.copies;
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}
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}
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total += score;
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}
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return total;
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}
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fn parseCards(content: []const u8) !std.ArrayList(Card) {
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var lines = std.mem.split(u8, content, "\n");
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var cards = std.ArrayList(Card).init(std.heap.page_allocator);
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while (lines.next()) |line| {
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if (line.len == 0) {
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continue;
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}
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// break line up on :
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var parts = std.mem.split(u8, line, ": ");
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_ = parts.next();
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// break the 2nd part up by |
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var sections = std.mem.split(u8, parts.next().?, " | ");
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// split the left part up on spaces
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var nums = std.mem.split(u8, sections.next().?, " ");
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var winning = std.ArrayList(u8).init(std.heap.page_allocator);
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while (nums.next()) |d| {
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if (d.len > 0) {
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try winning.append(try std.fmt.parseInt(u8, d, 10));
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}
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}
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// split the right part up on spaces
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nums = std.mem.split(u8, sections.next().?, " ");
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var have = std.ArrayList(u8).init(std.heap.page_allocator);
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while (nums.next()) |d| {
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if (d.len > 0) {
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try have.append(try std.fmt.parseInt(u8, d, 10));
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}
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}
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try cards.append(Card{ .winning = winning, .have = have, .copies = 1 });
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}
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return cards;
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}
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