1 // The Computer Language Benchmarks Game
2 // http://benchmarksgame.alioth.debian.org/
4 // contributed by the Rust Project Developers
6 // Copyright (c) 2013-2014 The Rust Project Developers
8 // All rights reserved.
10 // Redistribution and use in source and binary forms, with or without
11 // modification, are permitted provided that the following conditions
14 // - Redistributions of source code must retain the above copyright
15 // notice, this list of conditions and the following disclaimer.
17 // - Redistributions in binary form must reproduce the above copyright
18 // notice, this list of conditions and the following disclaimer in
19 // the documentation and/or other materials provided with the
22 // - Neither the name of "The Computer Language Benchmarks Game" nor
23 // the name of "The Computer Language Shootout Benchmarks" nor the
24 // names of its contributors may be used to endorse or promote
25 // products derived from this software without specific prior
26 // written permission.
28 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
31 // FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
32 // COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
33 // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
34 // (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
35 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 // HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
37 // STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
38 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
39 // OF THE POSSIBILITY OF SUCH DAMAGE.
41 // no-pretty-expanded FIXME #15189
43 #![feature(associated_types)]
45 use std::iter::repeat;
47 use std::sync::mpsc::channel;
48 use std::thread::Thread;
54 // returns an infinite iterator of repeated applications of f to x,
55 // i.e. [x, f(x), f(f(x)), ...], as haskell iterate function.
56 fn iterate<'a, T>(x: T, f: |&T|: 'a -> T) -> Iterate<'a, T> {
57 Iterate {f: f, next: x}
59 struct Iterate<'a, T> {
63 impl<'a, T> Iterator for Iterate<'a, T> {
66 fn next(&mut self) -> Option<T> {
67 let mut res = (self.f)(&self.next);
68 std::mem::swap(&mut res, &mut self.next);
73 // a linked list using borrowed next.
76 Cons(T, &'a List<'a, T>)
78 struct ListIterator<'a, T:'a> {
81 impl<'a, T> List<'a, T> {
82 fn iter(&'a self) -> ListIterator<'a, T> {
83 ListIterator{cur: self}
86 impl<'a, T> Iterator for ListIterator<'a, T> {
89 fn next(&mut self) -> Option<&'a T> {
92 List::Cons(ref elt, next) => {
104 // Takes a pieces p on the form [(y1, x1), (y2, x2), ...] and returns
105 // every possible transformations (the 6 rotations with their
106 // corresponding mirrored piece), with, as minimum coordinates, (0,
107 // 0). If all is false, only generate half of the possibilities (used
108 // to break the symmetry of the board).
109 fn transform(piece: Vec<(int, int)> , all: bool) -> Vec<Vec<(int, int)>> {
110 let mut res: Vec<Vec<(int, int)>> =
112 iterate(piece, |rot| rot.iter().map(|&(y, x)| (x + y, -y)).collect())
113 .take(if all {6} else {3})
115 .flat_map(|cur_piece| {
116 iterate(cur_piece, |mir| mir.iter().map(|&(y, x)| (x, y)).collect())
120 // translating to (0, 0) as minimum coordinates.
121 for cur_piece in res.iter_mut() {
122 let (dy, dx) = *cur_piece.iter().min_by(|e| *e).unwrap();
123 for &(ref mut y, ref mut x) in cur_piece.iter_mut() {
131 // A mask is a piece somewhere on the board. It is represented as a
132 // u64: for i in the first 50 bits, m[i] = 1 if the cell at (i/5, i%5)
133 // is occupied. m[50 + id] = 1 if the identifier of the piece is id.
135 // Takes a piece with minimum coordinate (0, 0) (as generated by
136 // transform). Returns the corresponding mask if p translated by (dy,
137 // dx) is on the board.
138 fn mask(dy: int, dx: int, id: uint, p: &Vec<(int, int)>) -> Option<u64> {
139 let mut m = 1 << (50 + id);
140 for &(y, x) in p.iter() {
141 let x = x + dx + (y + (dy % 2)) / 2;
142 if x < 0 || x > 4 {return None;}
144 if y < 0 || y > 9 {return None;}
145 m |= 1 << (y * 5 + x) as uint;
150 // Makes every possible masks. masks[i][id] correspond to every
151 // possible masks for piece with identifier id with minimum coordinate
153 fn make_masks() -> Vec<Vec<Vec<u64> > > {
155 vec!((0i,0i),(0,1),(0,2),(0,3),(1,3)),
156 vec!((0i,0i),(0,2),(0,3),(1,0),(1,1)),
157 vec!((0i,0i),(0,1),(0,2),(1,2),(2,1)),
158 vec!((0i,0i),(0,1),(0,2),(1,1),(2,1)),
159 vec!((0i,0i),(0,2),(1,0),(1,1),(2,1)),
160 vec!((0i,0i),(0,1),(0,2),(1,1),(1,2)),
161 vec!((0i,0i),(0,1),(1,1),(1,2),(2,1)),
162 vec!((0i,0i),(0,1),(0,2),(1,0),(1,2)),
163 vec!((0i,0i),(0,1),(0,2),(1,2),(1,3)),
164 vec!((0i,0i),(0,1),(0,2),(0,3),(1,2)));
166 // To break the central symmetry of the problem, every
167 // transformation must be taken except for one piece (piece 3
169 let transforms: Vec<Vec<Vec<(int, int)>>> =
170 pieces.into_iter().enumerate()
171 .map(|(id, p)| transform(p, id != 3))
174 range(0i, 50).map(|yx| {
175 transforms.iter().enumerate().map(|(id, t)| {
176 t.iter().filter_map(|p| mask(yx / 5, yx % 5, id, p)).collect()
181 // Check if all coordinates can be covered by an unused piece and that
182 // all unused piece can be placed on the board.
183 fn is_board_unfeasible(board: u64, masks: &Vec<Vec<Vec<u64>>>) -> bool {
184 let mut coverable = board;
185 for (i, masks_at) in masks.iter().enumerate() {
186 if board & 1 << i != 0 { continue; }
187 for (cur_id, pos_masks) in masks_at.iter().enumerate() {
188 if board & 1 << (50 + cur_id) != 0 { continue; }
189 for &cur_m in pos_masks.iter() {
190 if cur_m & board != 0 { continue; }
192 // if every coordinates can be covered and every
193 // piece can be used.
194 if coverable == (1 << 60) - 1 { return false; }
197 if coverable & 1 << i == 0 { return true; }
202 // Filter the masks that we can prove to result to unfeasible board.
203 fn filter_masks(masks: &mut Vec<Vec<Vec<u64>>>) {
204 for i in range(0, masks.len()) {
205 for j in range(0, (*masks)[i].len()) {
207 (*masks)[i][j].iter().map(|&m| m)
208 .filter(|&m| !is_board_unfeasible(m, masks))
214 // Gets the identifier of a mask.
215 fn get_id(m: u64) -> u8 {
216 for id in range(0u8, 10) {
217 if m & (1 << (id + 50) as uint) != 0 {return id;}
219 panic!("{:016x} does not have a valid identifier", m);
222 // Converts a list of mask to a Vec<u8>.
223 fn to_vec(raw_sol: &List<u64>) -> Vec<u8> {
224 let mut sol = repeat('.' as u8).take(50).collect::<Vec<_>>();
225 for &m in raw_sol.iter() {
226 let id = '0' as u8 + get_id(m);
227 for i in range(0u, 50) {
236 // Prints a solution in Vec<u8> form.
237 fn print_sol(sol: &Vec<u8>) {
238 for (i, c) in sol.iter().enumerate() {
239 if (i) % 5 == 0 { println!(""); }
240 if (i + 5) % 10 == 0 { print!(" "); }
241 print!("{} ", *c as char);
246 // The data managed during the search
248 // Number of solution found.
250 // Lexicographically minimal solution found.
252 // Lexicographically maximal solution found.
257 Data {nb: 0, min: vec!(), max: vec!()}
259 fn reduce_from(&mut self, other: Data) {
261 let Data { min: min, max: max, ..} = other;
262 if min < self.min { self.min = min; }
263 if max > self.max { self.max = max; }
267 // Records a new found solution. Returns false if the search must be
269 fn handle_sol(raw_sol: &List<u64>, data: &mut Data) {
270 // because we break the symmetry, 2 solutions correspond to a call
271 // to this method: the normal solution, and the same solution in
272 // reverse order, i.e. the board rotated by half a turn.
274 let sol1 = to_vec(raw_sol);
275 let sol2: Vec<u8> = sol1.iter().rev().map(|x| *x).collect();
278 data.min = sol1.clone();
279 data.max = sol1.clone();
282 if sol1 < data.min {data.min = sol1;}
283 else if sol1 > data.max {data.max = sol1;}
284 if sol2 < data.min {data.min = sol2;}
285 else if sol2 > data.max {data.max = sol2;}
289 masks: &Vec<Vec<Vec<u64>>>,
295 // Search for the lesser empty coordinate.
296 while board & (1 << i) != 0 && i < 50 {i += 1;}
297 // the board is full: a solution is found.
298 if i >= 50 {return handle_sol(&cur, data);}
299 let masks_at = &masks[i];
301 // for every unused piece
302 for id in range(0u, 10).filter(|&id| board & (1 << (id + 50)) == 0) {
303 // for each mask that fits on the board
304 for m in masks_at[id].iter().filter(|&m| board & *m == 0) {
305 // This check is too costly.
306 //if is_board_unfeasible(board | m, masks) {continue;}
307 search(masks, board | *m, i + 1, List::Cons(*m, &cur), data);
312 fn par_search(masks: Vec<Vec<Vec<u64>>>) -> Data {
313 let masks = Arc::new(masks);
314 let (tx, rx) = channel();
316 // launching the search in parallel on every masks at minimum
318 for m in (*masks)[0].iter().flat_map(|masks_pos| masks_pos.iter()) {
319 let masks = masks.clone();
322 Thread::spawn(move|| {
323 let mut data = Data::new();
324 search(&*masks, m, 1, List::Cons(m, &List::Nil), &mut data);
325 tx.send(data).unwrap();
329 // collecting the results
331 let mut data = rx.recv().unwrap();
332 for d in rx.iter() { data.reduce_from(d); }
337 let mut masks = make_masks();
338 filter_masks(&mut masks);
339 let data = par_search(masks);
340 println!("{} solutions found", data.nb);
341 print_sol(&data.min);
342 print_sol(&data.max);