src/day13.zig

@@ -1,136 +0,0 @@
-const std = @import("std");
-const util = @import("util.zig");
-const mem = std.mem;
-
-pub fn main() !void {
-    const input = @embedFile("data/day13.txt");
-    const sln = try solve(util.gpa, input);
-    std.debug.print("{d}\n", .{sln.a});
-    std.debug.print("{d}\n", .{sln.b});
-}
-
-const Solution = struct {
-    a: usize,
-    b: usize,
-};
-
-fn transpose(alloc: mem.Allocator, grid: []const []const u8) ![]const []const u8 {
-    std.debug.assert(grid.len > 0 and grid[0].len > 0);
-    var g = try alloc.alloc([]u8, grid[0].len);
-    for (0..grid[0].len) |i| {
-        g[i] = try alloc.alloc(u8, grid.len);
-    }
-    for (0..grid.len) |i| {
-        for (0..grid[i].len) |j| {
-            g[j][i] = grid[i][j];
-        }
-    }
-    return g;
-}
-
-fn findReflection(input: []const []const u8, err_tolerance: usize) ?usize {
-    if (input.len == 0) return 0;
-
-    const h = input.len;
-    const w = input[0].len;
-
-    for (0..h - 1) |scan| {
-        var offset: usize = 0;
-        var col: usize = 0;
-        var errors: usize = 0;
-        while (true) {
-            if (input[scan - offset][col] != input[scan + offset + 1][col]) {
-                errors += 1;
-            }
-            if (errors > err_tolerance + 1) {
-                break;
-            }
-            col = (col + 1) % w;
-            if (col == 0) offset += 1;
-            if (scan < offset or scan + offset + 1 >= h) {
-                if (errors == err_tolerance) return scan + 1;
-                break;
-            }
-        }
-    }
-
-    return null;
-}
-
-fn solve(alloc: mem.Allocator, input: []const u8) !Solution {
-    var curr_pattern = std.ArrayList([]const u8).init(alloc);
-    defer curr_pattern.deinit();
-
-    var it = util.splitLines(input);
-    var sums = [2]usize{ 0, 0 };
-    while (it.next()) |line| {
-        if (line.len == 0) {
-            const pattern = try curr_pattern.toOwnedSlice();
-            defer alloc.free(pattern);
-            for (0..2) |et| {
-                if (findReflection(pattern, et)) |score| {
-                    sums[et] += 100 * score;
-                } else {
-                    const t = try transpose(alloc, pattern);
-                    sums[et] += findReflection(t, et) orelse unreachable;
-
-                    // Ew.
-                    for (t) |r| {
-                        alloc.free(r);
-                    }
-                    alloc.free(t);
-                }
-            }
-        } else {
-            try curr_pattern.append(line);
-        }
-    }
-
-    return .{ .a = sums[0], .b = sums[1] };
-}
-
-test "silver" {
-    const input =
-        \\#.##..##.
-        \\..#.##.#.
-        \\##......#
-        \\##......#
-        \\..#.##.#.
-        \\..##..##.
-        \\#.#.##.#.
-        \\
-        \\#...##..#
-        \\#....#..#
-        \\..##..###
-        \\#####.##.
-        \\#####.##.
-        \\..##..###
-        \\#....#..#
-        \\
-    ;
-    const sln = try solve(std.testing.allocator, input);
-    try std.testing.expectEqual(@as(usize, 405), sln.a);
-}
-
-test "gold" {
-    const input =
-        \\#.##..##.
-        \\..#.##.#.
-        \\##......#
-        \\##......#
-        \\..#.##.#.
-        \\..##..##.
-        \\#.#.##.#.
-        \\
-        \\#...##..#
-        \\#....#..#
-        \\..##..###
-        \\#####.##.
-        \\#####.##.
-        \\..##..###
-        \\#....#..#
-        \\
-    ;
-    const sln = try solve(std.testing.allocator, input);
-    try std.testing.expectEqual(@as(usize, 400), sln.b);
-}