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const std = @import("std");
const mecha = @import("mecha");
const print = std.debug.print;
pub fn solve(part: []u8, buffer: []u8, allocator: std.mem.Allocator) !void {
if (std.mem.eql(u8, part, "1")) {
try part1(buffer, allocator);
} else {
try part2(buffer, allocator);
}
}
fn part1(buffer: []const u8, allocator: std.mem.Allocator) !void {
var disk = std.ArrayList(i32).init(allocator);
defer disk.deinit();
var free = false;
var id: i32 = 0;
for (buffer) |block_char| {
if (block_char == '\n') break;
const block = block_char - '0';
if (free) {
for (0..block) |_| {
try disk.append(-1);
}
} else {
for (0..block) |_| {
try disk.append(id);
}
id += 1;
}
free = !free;
}
var start_i: usize = 0;
var end_i: usize = disk.items.len - 1;
while (start_i < end_i) {
while (disk.items[start_i] != -1) : (start_i += 1) {}
while (disk.items[end_i] == -1) : (end_i -= 1) {}
disk.items[start_i] = disk.items[end_i];
start_i += 1;
end_i -= 1;
}
var checksum: usize = 0;
for (disk.items[0 .. end_i + 1], 0..) |file, index| {
if (file == -1) continue;
const f: usize = @intCast(file);
checksum += f * index;
}
print("{d}\n", .{checksum});
}
fn part2(buffer: []const u8, allocator: std.mem.Allocator) !void {
var categories: [9]std.ArrayList(std.meta.Tuple(&.{ usize, i32 })) = undefined;
for (&categories) |*cat| {
cat.* = std.ArrayList(std.meta.Tuple(&.{ usize, i32 })).init(allocator);
errdefer cat.deinit();
}
var counters: [9]usize = undefined;
@memset(&counters, 0);
var cid: i32 = @intCast((buffer.len - 1) / 2);
while (cid >= 0) {
const block = buffer[@intCast(cid * 2)] - '0';
for (block - 1..9) |n| {
try categories[n].append(.{ block, cid });
}
cid -= 1;
}
var set = std.AutoHashMap(usize, void).init(allocator);
defer set.deinit();
var checksum: usize = 0;
var id: usize = 0;
var empty = false;
var index: usize = 0;
for (buffer) |block_char| {
if (block_char == '\n') break;
var block: usize = block_char - '0';
if (empty) {
while (block > 0) {
var found_capacity: usize = 0;
var found_item: std.meta.Tuple(&.{ usize, i32 }) = undefined;
for (categories, 0..) |list, i| {
if (block > i + 1) continue;
if (list.items.len - counters[i] > 0) {
for (counters[i]..list.items.len) |k| {
if (set.contains(@intCast(list.items[k][1]))) {
counters[i] += 1;
} else {
break;
}
}
if (found_capacity == 0 and counters[i] < list.items.len) {
found_capacity = i + 1;
found_item = list.items[counters[i]];
counters[i] += 1;
} else {
break;
}
} else {
break;
}
}
if (found_capacity == 0) {
index += block;
break;
}
block -= found_item[0];
const idd: usize = @intCast(found_item[1]);
if (!set.contains(idd)) {
try set.put(idd, {});
for (0..found_item[0]) |_| {
checksum += idd * index;
index += 1;
}
}
}
} else {
if (!set.contains(id)) {
try set.put(id, {});
for (0..block) |_| {
checksum += id * index;
index += 1;
}
} else {
index += block;
}
id += 1;
}
empty = !empty;
}
for (&categories) |*cat| {
cat.*.deinit();
}
print("{d}\n", .{checksum});
}
|
