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const std = @import("std");
const Allocator = std.mem.Allocator;
const stdout = std.io.getStdOut().writer();
var bufferedStdout = std.io.bufferedWriter(stdout);
const bufout = bufferedStdout.writer();
const Move = enum {
horizontal,
left,
right,
fn toChar(self: Move) u8 {
return switch (self) {
Move.horizontal => 'H',
Move.left => 'L',
Move.right => 'R',
};
}
};
const Position = struct {
y: u32,
x: u32,
fn isBottomRight(self: Position) bool {
return self.y == 0 and self.x == 0;
}
fn move(self: Position, m: Move) ?Position {
return switch (m) {
Move.horizontal => .{
.y = self.y,
.x = if (self.x > 0) self.x - 1 else return null,
},
Move.left => .{
.y = if (self.y > 0) self.y - 1 else return null,
.x = self.x + 1,
},
Move.right => .{
.y = if (self.y > 0) self.y - 1 else return null,
.x = self.x,
},
};
}
fn printDirs(self: Position, dirs: []u8, depth: u32) anyerror!void {
if (self.isBottomRight()) {
try bufout.print("{s}\n", .{dirs[0..depth]});
return;
}
for ([_]Move{ Move.horizontal, Move.left, Move.right }) |m| {
const pos = self.move(m) orelse continue;
dirs[depth] = m.toChar();
try pos.printDirs(dirs, depth + 1);
}
}
};
pub fn main() !void {
const argv = std.os.argv;
if (argv.len != 2)
return error.InvalidArguments;
const size = try std.fmt.parseInt(u32, std.mem.span(argv[1]), 10);
var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
defer arena.deinit();
const allocator = &arena.allocator;
const position = Position{ .y = size, .x = 0 };
var dirs = try allocator.alloc(u8, 2 * size);
try position.printDirs(dirs, 0);
try bufferedStdout.flush();
}
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