sudoku

main.rs

use std::collections::HashSet;

struct Quad(Vec<Vec<Cell>>);
struct Row(Vec<Cell>);
struct Cell(u8);

impl Quad {
    fn is_valid(&self) -> bool {
        let mut values = HashSet::new();

        for row in self.0.iter() {
            for cell in row.iter() {
                if values.contains(&cell.0) {
                    return false;
                }

                values.insert(cell.0);
            }
        }

        true
    }
}

impl Row {
    fn is_valid(&self) -> bool {
        let mut values = HashSet::new();

        for cell in self.0.iter() {
            if values.contains(&cell.0) {
                return false;
            }

            values.insert(cell.0);
        }

        true
    }
}

fn solve_sudoku(grid: Vec<Vec<Cell>>) -> Option<Vec<Vec<Cell>>> {
    let mut quads = vec![];
    let mut rows = vec![];

    for i in (0..9).step_by(3) {
        for j in (0..9).step_by(3) {
            let quad = Quad(
                grid[i..i + 3]
                    .iter()
                    .map(|row| row[j..j + 3].to_vec())
                    .collect(),
            );

            if !quad.is_valid() {
                return None;
            }

            quads.push(quad);
        }
    }

    for row in grid.iter() {
        let row = Row(row.to_vec());

        if !row.is_valid() {
            return None;
        }

        rows.push(row);
    }

    // Solve the Sudoku puzzle using the quads and rows...

    Some(grid)
}