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06ce20853a
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@ -14,15 +14,27 @@ const Solution = struct {
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b: usize,
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b: usize,
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};
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};
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fn findReflection(input: []const []const u8) usize {
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fn transpose(alloc: mem.Allocator, grid: []const []const u8) ![]const []const u8 {
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std.debug.assert(grid.len > 0 and grid[0].len > 0);
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var g = try alloc.alloc([]u8, grid[0].len);
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for (0..grid[0].len) |i| {
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g[i] = try alloc.alloc(u8, grid.len);
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}
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for (0..grid.len) |i| {
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for (0..grid[i].len) |j| {
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g[j][i] = grid[i][j];
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}
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}
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return g;
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}
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fn findReflection(input: []const []const u8, err_tolerance: usize) ?usize {
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if (input.len == 0) return 0;
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if (input.len == 0) return 0;
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std.debug.print("{s}\n", .{input});
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const h = input.len;
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const h = input.len;
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const w = input[0].len;
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const w = input[0].len;
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// Scan horizontal reflectivity
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for (0..h - 1) |scan| {
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hscan: for (0..h - 1) |scan| {
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var offset: usize = 0;
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var offset: usize = 0;
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var col: usize = 0;
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var col: usize = 0;
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var errors: usize = 0;
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var errors: usize = 0;
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@ -30,42 +42,19 @@ fn findReflection(input: []const []const u8) usize {
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if (input[scan - offset][col] != input[scan + offset + 1][col]) {
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if (input[scan - offset][col] != input[scan + offset + 1][col]) {
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errors += 1;
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errors += 1;
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}
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}
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if (errors > 1) {
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if (errors > err_tolerance + 1) {
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continue :hscan;
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break;
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}
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}
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std.debug.print("{}±{} {} [{}]\n", .{ scan, offset, col, errors });
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col = (col + 1) % w;
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col = (col + 1) % w;
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if (col == 0) offset += 1;
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if (col == 0) offset += 1;
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if (scan < offset or scan + offset + 1 >= h) {
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if (scan < offset or scan + offset + 1 >= h) {
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if (errors == 1) return (scan + 1) * 100;
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if (errors == err_tolerance) return scan + 1;
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continue :hscan;
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break;
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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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// Scan vertical reflectivity
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return null;
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vscan: for (0..w - 1) |scan| {
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var offset: usize = 0;
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var row: usize = 0;
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var errors: usize = 0;
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while (true) {
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if (input[row][scan - offset] != input[row][scan + offset + 1]) {
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errors += 1;
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}
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if (errors > 1) {
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continue :vscan;
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}
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std.debug.print("{} {}±{} [{}]\n", .{ row, scan, offset, errors });
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row = (row + 1) % h;
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if (row == 0) offset += 1;
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if (scan < offset or scan + offset + 1 >= w) {
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if (errors == 1) return scan + 1;
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continue :vscan;
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}
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}
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}
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unreachable;
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}
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}
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fn solve(alloc: mem.Allocator, input: []const u8) !Solution {
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fn solve(alloc: mem.Allocator, input: []const u8) !Solution {
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@ -73,20 +62,31 @@ fn solve(alloc: mem.Allocator, input: []const u8) !Solution {
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defer curr_pattern.deinit();
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defer curr_pattern.deinit();
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var it = util.splitLines(input);
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var it = util.splitLines(input);
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var sum: usize = 0;
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var sums = [2]usize{ 0, 0 };
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while (it.next()) |line| {
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while (it.next()) |line| {
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if (line.len == 0) {
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if (line.len == 0) {
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const pattern = try curr_pattern.toOwnedSlice();
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const pattern = try curr_pattern.toOwnedSlice();
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defer alloc.free(pattern);
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defer alloc.free(pattern);
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const score = findReflection(pattern);
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for (0..2) |et| {
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std.debug.print("... {}\n", .{score});
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if (findReflection(pattern, et)) |score| {
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sum += score;
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sums[et] += 100 * score;
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} else {
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const t = try transpose(alloc, pattern);
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sums[et] += findReflection(t, et) orelse unreachable;
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// Ew.
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for (t) |r| {
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alloc.free(r);
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}
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alloc.free(t);
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}
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}
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} else {
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} else {
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try curr_pattern.append(line);
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try curr_pattern.append(line);
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}
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}
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}
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}
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return .{ .a = 405, .b = sum };
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return .{ .a = sums[0], .b = sums[1] };
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}
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}
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test "silver" {
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test "silver" {
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@ -108,9 +108,8 @@ test "silver" {
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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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_ = input;
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const sln = try solve(std.testing.allocator, input);
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// const sln = try solve(std.testing.allocator, input);
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try std.testing.expectEqual(@as(usize, 405), sln.a);
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// try std.testing.expectEqual(@as(usize, 405), sln.a);
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}
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}
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test "gold" {
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test "gold" {
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