Apply naked single strategy to solve a NYT easy sudoku.

src/validator.rs

@@ -0,0 +1,63 @@
+use crate::{board::Board, square::Square};
+
+pub enum BoardState {
+    Finished,
+    Broken(u8),
+    InProgress,
+}
+
+fn are_unique<T>(iter: T) -> bool
+where
+    T: Iterator<Item = u8>,
+{
+    let mut bitmap: bitmaps::Bitmap<10> = bitmaps::Bitmap::new();
+
+    for item in iter {
+        if bitmap.get(item as usize) {
+            return false;
+        }
+        bitmap.set(item as usize, true);
+    }
+    true
+}
+
+pub fn validate_board(board: &Board) -> BoardState {
+    for r in 0..9 {
+        if !are_unique(board.row(r).filter_map(|sq| match sq {
+            Square::Value(x) => Some(x),
+            _ => None,
+        })) {
+            // TODO: Add the index.
+            return BoardState::Broken(0);
+        }
+    }
+
+    for c in 0..9 {
+        if !are_unique(board.col(c).filter_map(|sq| match sq {
+            Square::Value(x) => Some(x),
+            _ => None,
+        })) {
+            // TODO: Add the index.
+            return BoardState::Broken(0);
+        }
+    }
+
+    for b in 0..9 {
+        if !are_unique(board.boxn(b).filter_map(|sq| match sq {
+            Square::Value(x) => Some(x),
+            _ => None,
+        })) {
+            // TODO: Add the index.
+            return BoardState::Broken(0);
+        }
+    }
+
+    if board.squares.iter().any(|sq| match sq {
+        Square::Options(_) => true,
+        _ => false,
+    }) {
+        BoardState::InProgress
+    } else {
+        BoardState::Finished
+    }
+}