116 lines
3.3 KiB
Rust
116 lines
3.3 KiB
Rust
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//! Killer Sudoku.
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//!
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//! https://en.wikipedia.org/wiki/Killer_sudoku
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extern crate puzzle_solver;
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use puzzle_solver::{LinExpr,Puzzle,Solution,Val,VarToken};
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const SQRT_SIZE: usize = 3;
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const SIZE: usize = 9;
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type Board = [[Val; SIZE]; SIZE];
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type Point = (usize, usize);
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fn make_killer_sudoku(board: &[(Val, Vec<Point>)]) -> (Puzzle, Vec<Vec<VarToken>>) {
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let mut sys = Puzzle::new();
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let vars = sys.new_vars_with_candidates_2d(SIZE, SIZE, &[1,2,3,4,5,6,7,8,9]);
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for y in 0..SIZE {
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sys.all_different(&vars[y]);
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}
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for x in 0..SIZE {
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sys.all_different(vars.iter().map(|row| &row[x]));
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}
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for block in 0..SIZE {
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let x0 = SQRT_SIZE * (block % SQRT_SIZE);
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let y0 = SQRT_SIZE * (block / SQRT_SIZE);
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sys.all_different((0..SIZE).map(|n|
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&vars[y0 + (n / SQRT_SIZE)][x0 + (n % SQRT_SIZE)]));
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}
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for &(total, ref points) in board.iter() {
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sys.equals(total, points.iter().fold(LinExpr::from(0), |sum, &(x,y)| sum + vars[y][x]));
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}
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(sys, vars)
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}
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fn print_sudoku(dict: &Solution, vars: &Vec<Vec<VarToken>>) {
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for y in 0..SIZE {
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if y % SQRT_SIZE == 0 {
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println!();
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}
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for x in 0..SIZE {
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print!("{}{}",
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if x % SQRT_SIZE == 0 { " " } else { "" },
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dict[vars[y][x]]);
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}
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println!();
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}
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}
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fn verify_sudoku(dict: &Solution, vars: &Vec<Vec<VarToken>>, expected: &Board) {
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for y in 0..SIZE {
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for x in 0..SIZE {
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assert_eq!(dict[vars[y][x]], expected[y][x]);
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}
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}
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}
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#[test]
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fn killersudoku_wikipedia() {
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let puzzle = [
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( 3, vec![(0,0), (1,0)]),
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(15, vec![(2,0), (3,0), (4,0)]),
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(22, vec![(5,0), (4,1), (5,1), (4,2)]),
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( 4, vec![(6,0), (6,1)]),
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(16, vec![(7,0), (7,1)]),
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(15, vec![(8,0), (8,1), (8,2), (8,3)]),
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(25, vec![(0,1), (1,1), (0,2), (1,2)]),
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(17, vec![(2,1), (3,1)]),
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( 9, vec![(2,2), (3,2), (3,3)]),
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( 8, vec![(5,2), (5,3), (5,4)]),
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(20, vec![(6,2), (7,2), (6,3)]),
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( 6, vec![(0,3), (0,4)]),
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(14, vec![(1,3), (2,3)]),
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(17, vec![(4,3), (4,4), (4,5)]),
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(17, vec![(7,3), (6,4), (7,4)]),
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(13, vec![(1,4), (2,4), (1,5)]),
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(20, vec![(3,4), (3,5), (3,6)]),
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(12, vec![(8,4), (8,5)]),
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(27, vec![(0,5), (0,6), (0,7), (0,8)]),
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( 6, vec![(2,5), (1,6), (2,6)]),
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(20, vec![(5,5), (5,6), (6,6)]),
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( 6, vec![(6,5), (7,5)]),
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(10, vec![(4,6), (3,7), (4,7), (3,8)]),
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(14, vec![(7,6), (8,6), (7,7), (8,7)]),
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( 8, vec![(1,7), (1,8)]),
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(16, vec![(2,7), (2,8)]),
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(15, vec![(5,7), (6,7)]),
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(13, vec![(4,8), (5,8), (6,8)]),
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(17, vec![(7,8), (8,8)]),
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];
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let expected = [
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[ 2,1,5, 6,4,7, 3,9,8 ],
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[ 3,6,8, 9,5,2, 1,7,4 ],
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[ 7,9,4, 3,8,1, 6,5,2 ],
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[ 5,8,6, 2,7,4, 9,3,1 ],
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[ 1,4,2, 5,9,3, 8,6,7 ],
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[ 9,7,3, 8,1,6, 4,2,5 ],
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[ 8,2,1, 7,3,9, 5,4,6 ],
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[ 6,5,9, 4,2,8, 7,1,3 ],
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[ 4,3,7, 1,6,5, 2,8,9 ] ];
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let (mut sys, vars) = make_killer_sudoku(&puzzle);
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let dict = sys.solve_any().expect("solution");
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print_sudoku(&dict, &vars);
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verify_sudoku(&dict, &vars, &expected);
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println!("killersudoku_wikipedia: {} guesses", sys.num_guesses());
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}
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