56 lines
1.4 KiB
Zig
56 lines
1.4 KiB
Zig
const std = @import("std");
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const input = @embedFile("input");
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pub fn main() anyerror!void {
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var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
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defer arena.deinit();
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const allocator = arena.allocator();
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const result = try solve(input, 12, allocator);
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try std.io.getStdOut().writer().print("{}\n", .{result});
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}
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fn solve(puzzle: []const u8, width: u8, allocator: std.mem.Allocator) !u64 {
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var it = std.mem.tokenize(u8, puzzle, "\n");
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var bits = std.ArrayList(u64).init(allocator);
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defer bits.deinit();
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if (it.next()) |line| {
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for (line) |c| {
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var v: u8 = 0;
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if (c == '1') {
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v = 1;
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}
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try bits.append(v);
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}
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}
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var len: usize = 1;
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while (it.next()) |line| : (len += 1) {
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for (line) |c, i| {
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if (c == '1') {
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bits.items[i] += 1;
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}
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}
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}
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var gamma: u64 = 0;
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var epsilon: u64 = 0;
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var i: usize = 0;
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while (i < width) : (i += 1) {
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gamma <<= 1;
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epsilon <<= 1;
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if (bits.items[i] > len / 2) {
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gamma += 1;
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} else {
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epsilon += 1;
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}
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}
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return gamma * epsilon;
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}
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test "solve" {
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const example = @embedFile("example");
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try std.testing.expectEqual(solve(example, 5, std.testing.allocator), 198);
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}
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