Sudoku: Difference between revisions

=={{header|Rust}}==

{{trans|Ada}}

<lang rust>

type SudokuArType = [u8; 81];

fn check_validity( val : u8, x : usize, y : usize, sudoku_ar : &mut SudokuArType ) -> bool{

for i in 0..=8 {

if ( sudoku_ar[y * 9 + i] == val ) || ( sudoku_ar[i * 9 + x] == val ) {

return false

}

}

let startx : usize = ( x / 3 ) * 3;

let starty : usize = ( y / 3 ) * 3;

for i in starty..=(starty + 2) {

for j in startx..=(startx + 2) {

if sudoku_ar[i * 9 + j] == val {

return false

}

}

}

true

}

fn place_number( pos: usize, sudoku_ar: &mut SudokuArType ) -> bool {

let mut ret : bool;

if pos == 81 {

return true

}

if sudoku_ar[pos] > 0 {

ret = place_number( pos + 1, sudoku_ar );

if ret == true {

return true

} else {

return false

}

}

for n in 1..=9 {

if check_validity(n, pos % 9, pos / 9, sudoku_ar) == true {

sudoku_ar[pos] = n;

ret = place_number( pos + 1, sudoku_ar );

if ret == true{

return true;

}

sudoku_ar[pos] = 0;

}

}

false

}

fn pretty_print( sudoku_ar : SudokuArType ) {

let line_sep = "------+------+------";

println!("{}",line_sep);

for i in 0..sudoku_ar.len() {

print!("{} ", sudoku_ar[i] );

if (i + 1) % 3 == 0 && !( (i + 1) % 9 == 0 ) {

print!("| ");

}

if (i+1) % 9 == 0 {

println!(" ");

}

if (i+1) % 27 == 0 {

println!("{}", line_sep);

}

}

}

fn solve( sudoku_ar : &mut SudokuArType) -> bool {

place_number( 0, sudoku_ar )

}

fn main() {

let mut sudoku_ar: SudokuArType = [

8,5,0,0,0,2,4,0,0,

7,2,0,0,0,0,0,0,9,

0,0,4,0,0,0,0,0,0,

0,0,0,1,0,7,0,0,2,

3,0,5,0,0,0,9,0,0,

0,4,0,0,0,0,0,0,0,

0,0,0,0,8,0,0,7,0,

0,1,7,0,0,0,0,0,0,

0,0,0,0,3,6,0,4,0

];

if solve( &mut sudoku_ar ) == false {

println!("Unsolvable");

} else {

pretty_print( sudoku_ar );

}

}

{{out}}

<pre>

------+------+------

8 5 9 | 6 1 2 | 4 3 7

7 2 3 | 8 5 4 | 1 6 9

1 6 4 | 3 7 9 | 5 2 8

------+------+------

9 8 6 | 1 4 7 | 3 5 2

3 7 5 | 2 6 8 | 9 1 4

2 4 1 | 5 9 3 | 7 8 6

------+------+------

4 3 2 | 9 8 1 | 6 7 5

6 1 7 | 4 2 5 | 8 9 3

5 9 8 | 7 3 6 | 2 4 1

------+------+------

</pre>