optionally reuse old values

src/cell.rs

@@ -9,15 +9,20 @@ pub struct Cell {
     pub state: u32,
 }
 
-pub fn init_grid() -> Vec<Vec<Cell>> {
+pub fn init_grid(option: Option<&Vec<Vec<Cell>>>) -> Vec<Vec<Cell>> {
     let mut grid: Vec<Vec<Cell>> = Vec::new();
     for j in 0..HEIGHT {
         let mut row: Vec<Cell> = Vec::new();
         for i in 0..WIDTH {
+            let mut value = rand::random::<u32>() % Q;
+            if let Some(g) = option {
+                value = g[j as usize][i as usize].state;
+            }
+
             row.push(Cell {
                 x: i,
                 y: j,
-                state: 0,
+                state: value,
             });
         }
         grid.push(row);