aoc2022/day5/puzzle2.zig

99 lines
2.7 KiB
Zig
Raw Normal View History

2022-12-05 17:45:45 +00:00
const std = @import("std");
const mem = std.mem;
const fmt = std.fmt;
const CharList = std.ArrayList(u8);
const input = @embedFile("input");
const n_crates = 9;
fn parseCrates(input_iterator: *mem.SplitIterator(u8), comptime n: u8, allocator: mem.Allocator) []CharList {
// Return value
var crates = allocator.alloc(CharList, n) catch unreachable;
for (crates) |*crate| {
crate.* = CharList.init(allocator);
}
// Make sure it's pointing to the start
input_iterator.reset();
while (input_iterator.next()) |line| {
// Parse until empty line
if (line.len == 0) break;
// Keep track of which crate we are in
var index: usize = 0;
for (line) |char, i| {
switch (char) {
'A'...'Z' => crates[index].insert(0, char) catch unreachable,
else => index = i / 4,
}
}
}
return crates;
}
fn destroyCrates(crates: []CharList) void {
for (crates) |*crate| {
crate.*.deinit();
}
}
pub fn main() !void {
var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
defer arena.deinit();
const allocator = arena.allocator();
var input_iterator = mem.split(u8, input, "\n");
var crates = parseCrates(&input_iterator, n_crates, allocator);
//defer destroyCrates(crates);
while (input_iterator.next()) |line| {
if (line.len == 0) continue;
// Print the state
for (crates) |crate, i| {
std.debug.print("{d} : {s}\n", .{ i, crate.items });
}
// Parsing the line to get action
var line_iterator = mem.split(u8, line, " ");
// n, src, dst
var numbers = [_]u8{undefined} ** 3;
var index: usize = 0;
while (line_iterator.next()) |word| {
// Get a number and asign or go to next word
numbers[index] = fmt.parseInt(u8, word, 10) catch continue;
if (index == 3) {
std.debug.print("Word parsing error, index out of bounds", .{});
unreachable;
}
index += 1;
}
// Performing the action
var i: usize = 0;
const n = numbers[0];
const src = numbers[1] - 1;
const dst = numbers[2] - 1;
std.debug.print("Move {} from {} to {}\n", .{n, src, dst});
var tmp_crates = CharList.init(allocator);
while (i < n) : (i += 1) {
tmp_crates.insert(0, crates[src].pop()) catch unreachable;
}
crates[dst].appendSlice(tmp_crates.items) catch unreachable;
}
// Printing the final state
for (crates) |crate, i| {
std.debug.print("{d} : {s}\n", .{ i, crate.items });
}
}