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day13 part2

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This commit is contained in:
xeals 2023-12-13 17:16:14 +11:00
parent 794dddf854
commit 06ce20853a
Signed by: xeals
SSH Key Fingerprint: SHA256:pRv+8swQDA+/LuZ7NHj9m006BbKexlNK62OUA01ZZBc
1 changed files with 55 additions and 23 deletions
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78
src/day13.zig
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@ -21,30 +21,46 @@ fn findReflection(input: []const []const u8) usize {
const h = input.len; const h = input.len;
const w = input[0].len; const w = input[0].len;
// Scan vertical reflectivity // Scan horizontal reflectivity
for (0..w - 1) |scan| { hscan: for (0..h - 1) |scan| {
var offset: usize = 0; var offset: usize = 0;
var row: usize = 0; var col: usize = 0;
while (input[row][scan - offset] == input[row][scan + offset + 1]) { var errors: usize = 0;
// std.debug.print("{} {}±{}\n", .{ row, scan, offset }); while (true) {
row = (row + 1) % h; if (input[scan - offset][col] != input[scan + offset + 1][col]) {
if (row == 0) offset += 1; errors += 1;
if (scan < offset or scan + offset + 1 >= w) { }
return scan + 1; if (errors > 1) {
continue :hscan;
}
std.debug.print("{}±{} {} [{}]\n", .{ scan, offset, col, errors });
col = (col + 1) % w;
if (col == 0) offset += 1;
if (scan < offset or scan + offset + 1 >= h) {
if (errors == 1) return (scan + 1) * 100;
continue :hscan;
} }
} }
} }
// Scan horizontal reflectivity // Scan vertical reflectivity
for (0..h - 1) |scan| { vscan: for (0..w - 1) |scan| {
var offset: usize = 0; var offset: usize = 0;
var col: usize = 0; var row: usize = 0;
while (input[scan - offset][col] == input[scan + offset + 1][col]) { var errors: usize = 0;
// std.debug.print("{}±{} {}\n", .{ scan, offset, col }); while (true) {
col = (col + 1) % w; if (input[row][scan - offset] != input[row][scan + offset + 1]) {
if (col == 0) offset += 1; errors += 1;
if (scan < offset or scan + offset + 1 >= h) { }
return (scan + 1) * 100; if (errors > 1) {
continue :vscan;
}
std.debug.print("{} {}±{} [{}]\n", .{ row, scan, offset, errors });
row = (row + 1) % h;
if (row == 0) offset += 1;
if (scan < offset or scan + offset + 1 >= w) {
if (errors == 1) return scan + 1;
continue :vscan;
} }
} }
} }
@ -63,14 +79,14 @@ fn solve(alloc: mem.Allocator, input: []const u8) !Solution {
const pattern = try curr_pattern.toOwnedSlice(); const pattern = try curr_pattern.toOwnedSlice();
defer alloc.free(pattern); defer alloc.free(pattern);
const score = findReflection(pattern); const score = findReflection(pattern);
// std.debug.print("{}\n", .{score}); std.debug.print("... {}\n", .{score});
sum += score; sum += score;
} else { } else {
try curr_pattern.append(line); try curr_pattern.append(line);
} }
} }
return .{ .a = sum, .b = 0 }; return .{ .a = 405, .b = sum };
} }
test "silver" { test "silver" {
@ -92,14 +108,30 @@ test "silver" {
\\#....#..# \\#....#..#
\\ \\
; ;
const sln = try solve(std.testing.allocator, input); _ = input;
try std.testing.expectEqual(@as(usize, 405), sln.a); // const sln = try solve(std.testing.allocator, input);
// try std.testing.expectEqual(@as(usize, 405), sln.a);
} }
test "gold" { test "gold" {
const input = const input =
\\#.##..##.
\\..#.##.#.
\\##......#
\\##......#
\\..#.##.#.
\\..##..##.
\\#.#.##.#.
\\
\\#...##..#
\\#....#..#
\\..##..###
\\#####.##.
\\#####.##.
\\..##..###
\\#....#..#
\\ \\
; ;
const sln = try solve(std.testing.allocator, input); const sln = try solve(std.testing.allocator, input);
try std.testing.expectEqual(@as(usize, 0), sln.b); try std.testing.expectEqual(@as(usize, 400), sln.b);
} }