conway.rs

/*

2x grid, nxm
cell alive or dead
at most 8 neighbors
living cell with exactly 2 or 3 living neighbors stays alive, otherwise dies
dead cell with exactly 3 living neighbors becomes alive.


input = [
    [True,  False, True,  False],
    [False, False, False, True],
    [True,  True,  True,  False]
]
expected = [
    [False, False, False, False],
    [True,  False, False, True],
    [False, True,  True,  False]
]



*/

fn main() {
    let mut grid: Vec<Vec<bool>> = vec![
        vec![true, false, true, false],
        vec![false, false, false, true],
        vec![true, true, true, false],
    ];
    let expected: Vec<Vec<bool>> = vec![
        vec![false, false, false, false],
        vec![true, false, false, true],
        vec![false, true, true, false],
    ];
    let ROW_MAX = grid.len() - 1;
    let COL_MAX = grid.get(0).unwrap().len() - 1;

    let mut new_grid = grid.clone();

    for (ridx, row) in grid.clone().iter_mut().enumerate() {
        for (cidx, cell) in row.iter_mut().enumerate() {
            let mut neighbors: Vec<bool> = Vec::new();

            if ridx != 0 {
                if cidx == 0 {
                    // Left most column, no neighbors left
                } else {
                    neighbors.push(grid[ridx - 1][cidx - 1]);
                    neighbors.push(grid[ridx][cidx - 1]);
                    if ridx != ROW_MAX {
                        neighbors.push(grid[ridx + 1][cidx - 1]);
                    }
                }

                neighbors.push(grid[ridx - 1][cidx]);
                if ridx != ROW_MAX {
                    neighbors.push(grid[ridx + 1][cidx]);
                }

                if cidx != COL_MAX {
                    neighbors.push(grid[ridx - 1][cidx + 1]);
                    neighbors.push(grid[ridx][cidx + 1]);
                    if ridx != ROW_MAX {
                        neighbors.push(grid[ridx + 1][cidx + 1]);
                    }
                }
            } else {
                if cidx == 0 {
                    // Left most column, no neighbors left
                } else {
                    neighbors.push(grid[ridx][cidx - 1]);
                    if ridx != ROW_MAX {
                        neighbors.push(grid[ridx + 1][cidx - 1]);
                    }
                }

                if ridx != ROW_MAX {
                    neighbors.push(grid[ridx + 1][cidx]);
                }

                if cidx != COL_MAX {
                    neighbors.push(grid[ridx][cidx + 1]);
                    if ridx != ROW_MAX {
                        neighbors.push(grid[ridx + 1][cidx + 1]);
                    }
                }
            }

            let n_alive = neighbors.iter().filter(|&&n| n == true).count();

            if !((n_alive == 2 || n_alive == 3) && *cell) {
                new_grid[ridx][cidx] = false;
            }
            if n_alive == 3 && !*cell {
                new_grid[ridx][cidx] = true;
            }
        }
    }

    println!("output {:?}", new_grid);
    println!("expected {:?}", expected);

    println!("Grids Match?: {}", new_grid == expected);
}