row col block as different datasets.

unexpectedly this seems to be slower for now... :(

src/main.rs

@@ -1,5 +1,10 @@
+use std::time::Instant;
+
 struct SField {
     field: Vec<usize>,
+    rows: Vec<Vec<usize>>,
+    cols: Vec<Vec<usize>>,
+    blocks: Vec<Vec<usize>>,
     fixed: Vec<usize>,
     size: usize,
     block_size: usize,
@@ -88,8 +93,15 @@ impl SField {
             }
         });
 
+        let rows = SField::rows_from_plain_field(&field);
+        let cols = SField::cols_from_plain_field(&field);
+        let blocks = SField::blocks_from_plain_field(&field);
+
         SField {
             field,
+            rows,
+            cols,
+            blocks,
             fixed,
             size,
             block_size,
@@ -100,6 +112,51 @@ impl SField {
         }
     }
 
+    fn rows_from_plain_field(field: &[usize]) -> Vec<Vec<usize>> {
+        let mut rows = vec![vec![0; 9]; 9];
+        for row in 0..9 {
+            for col in 0..9 {
+                rows[row][col] = field[row * 9 + col];
+            }
+        }
+        rows
+    }
+
+    fn cols_from_plain_field(field: &[usize]) -> Vec<Vec<usize>> {
+        let mut cols = vec![vec![0; 9]; 9];
+        for row in 0..9 {
+            for col in 0..9 {
+                cols[col][row] = field[row * 9 + col];
+            }
+        }
+        cols
+    }
+
+    fn blocks_from_plain_field(field: &[usize]) -> Vec<Vec<usize>> {
+        fn get_block_with_pos(field: &[usize], pos: usize) -> Vec<usize> {
+            let block_start_row = pos / 9 / 3 * 3;
+            let block_start_col = pos % 9 / 3 * 3;
+
+            let mut block = vec![];
+
+            for r in 0..3 {
+                for c in 0..3 {
+                    block.push(field[9 * (block_start_row + r) + block_start_col + c])
+                }
+            }
+
+            block
+        }
+
+        let mut blocks = vec![];
+        let block_start_positions = [0, 3, 6, 27, 30, 33, 54, 57, 60];
+        for pos in block_start_positions {
+            blocks.push(get_block_with_pos(field, pos));
+        }
+
+        blocks
+    }
+
     fn build_possible_values_db(&mut self) {
         for idx in 0..self.num_fields {
             if self.fixed[idx] == 1 {
@@ -325,58 +382,103 @@ impl SField {
         unsafe { *self.field.get_unchecked(pos) }
     }
 
+    #[inline(always)]
+    fn get_x_y_block_blockoffset(&self) -> (usize, usize, usize, usize) {
+        // TODO:
+        // this only works for 3x3 sudoku
+        #[rustfmt::skip]
+        let block_nrs = [
+             0, 1, 2, 9,10,11,18,19,20,
+             3, 4, 5,12,13,14,21,22,23,
+             6, 7, 8,15,16,17,24,25,26,
+            27,28,29,36,37,38,45,46,47,
+            30,31,32,39,40,41,48,49,50,
+            33,34,35,42,43,44,51,52,53,
+            54,55,56,63,64,65,72,73,74,
+            57,58,59,66,67,68,75,76,77,
+            60,61,62,69,70,71,78,79,80,
+        ];
+
+        let y = self.pos / self.size;
+        let x = self.pos % self.size;
+
+        let block_field = unsafe { block_nrs.get_unchecked(self.pos) };
+
+        let block_nr = block_field / self.size;
+        let block_offset = block_field - (block_nr * self.size);
+
+        (x, y, block_nr, block_offset)
+    }
+
     #[inline(always)]
     fn set(&mut self, nr: usize) {
+        //assert_eq!(self.field, self.flatten_rows());
+        //assert_eq!(self.field, self.flatten_cols());
+        //assert_eq!(self.field, self.flatten_blocks());
+
         self.field[self.pos] = nr;
         self.pos_last_placed = self.pos;
-    }
 
-    #[inline(always)]
-    fn get_row(&self, row: &mut [usize; 9]) {
-        for (idx, row_elem) in row.iter_mut().enumerate() {
-            *row_elem = self.get_field_at_pos((self.pos / self.size) * self.size + idx);
-        }
-    }
+        // update rows, cols and blocks
+        // this is more expensive than only updating field but should be outweight
+        // by the fact that row_ok(), col_ok() and block_ok() just need to do simple
+        // lookups now
 
-    #[inline(always)]
-    fn get_col(&self, col: &mut [usize; 9]) {
-        for (idx, col_elem) in col.iter_mut().enumerate() {
-            *col_elem = self.get_field_at_pos(idx * self.size + self.pos % self.size);
-        }
-    }
+        let (x, y, block_nr, block_offset) = self.get_x_y_block_blockoffset();
 
-    #[inline(always)]
-    fn get_block(&self, block: &mut [usize; 9]) {
-        let block_start_row = self.pos / self.size / self.block_size * self.block_size;
-        let block_start_col = self.pos % self.size / self.block_size * self.block_size;
+        //println!("[{},{}] setting {}", y, x, nr);
 
-        for r in 0..self.block_size {
-            for c in 0..self.block_size {
-                block[r * self.block_size + c] =
-                    self.get_field_at_pos(self.size * (block_start_row + r) + block_start_col + c);
-            }
-        }
+        let row = unsafe { self.rows.get_unchecked_mut(y) };
+        let value = unsafe { row.get_unchecked_mut(x) };
+        *value = nr;
+
+        let col = unsafe { self.cols.get_unchecked_mut(x) };
+        let value = unsafe { col.get_unchecked_mut(y) };
+        *value = nr;
+
+        let block = unsafe { self.blocks.get_unchecked_mut(block_nr) };
+        let value = unsafe { block.get_unchecked_mut(block_offset) };
+        *value = nr;
+
+        //assert_eq!(self.field, self.flatten_rows());
+        //assert_eq!(self.field, self.flatten_cols());
+        //assert_eq!(self.field, self.flatten_blocks());
     }
 
     #[inline(always)]
     fn block_ok(&self, nr: usize) -> bool {
-        let mut block = [0; 9];
-        self.get_block(&mut block);
-        !block.contains(&nr)
+        // TODO
+        // works only on 3x3 sudoku
+        #[rustfmt::skip]
+        let block_nrs = [
+            0,0,0,1,1,1,2,2,2,
+            0,0,0,1,1,1,2,2,2,
+            0,0,0,1,1,1,2,2,2,
+            3,3,3,4,4,4,5,5,5,
+            3,3,3,4,4,4,5,5,5,
+            3,3,3,4,4,4,5,5,5,
+            6,6,6,7,7,7,8,8,8,
+            6,6,6,7,7,7,8,8,8,
+            6,6,6,7,7,7,8,8,8,
+        ];
+
+        let block_nr = unsafe { block_nrs.get_unchecked(self.pos) };
+        //println!("Block {}: {:?}", block_nr, self.blocks[*block_nr]);
+        !unsafe { self.blocks.get_unchecked(*block_nr) }.contains(&nr)
     }
 
     #[inline(always)]
     fn row_ok(&self, nr: usize) -> bool {
-        let mut row = [0; 9];
-        self.get_row(&mut row);
-        !row.contains(&nr)
+        let row_nr = self.pos / self.size;
+        //println!("{:?}", self.rows[row_nr]);
+        !unsafe { self.rows.get_unchecked(row_nr) }.contains(&nr)
     }
 
     #[inline(always)]
     fn col_ok(&self, nr: usize) -> bool {
-        let mut col = [0; 9];
-        self.get_col(&mut col);
-        !col.contains(&nr)
+        let col_nr = self.pos % self.size;
+        //println!("{:?}", self.cols[col_nr]);
+        !unsafe { self.cols.get_unchecked(col_nr) }.contains(&nr)
     }
 
     #[inline(always)]
@@ -401,10 +503,53 @@ impl SField {
 
     #[inline(always)]
     fn solve(&mut self) {
+        let now = Instant::now();
         if !self.solve_backtracking() {
             println!("there is no solution.");
         }
+        println!("took {:.3} seconds", now.elapsed().as_secs_f64());
     }
+
+    //fn flatten_blocks(&self) -> Vec<usize> {
+    //#[rustfmt::skip]
+    //let block_nrs = [
+    //0, 1, 2, 9,10,11,18,19,20,
+    //3, 4, 5,12,13,14,21,22,23,
+    //6, 7, 8,15,16,17,24,25,26,
+    //27,28,29,36,37,38,45,46,47,
+    //30,31,32,39,40,41,48,49,50,
+    //33,34,35,42,43,44,51,52,53,
+    //54,55,56,63,64,65,72,73,74,
+    //57,58,59,66,67,68,75,76,77,
+    //60,61,62,69,70,71,78,79,80,
+    //];
+
+    //let mut flattened = Vec::with_capacity(self.num_fields);
+    //for (idx, nr) in block_nrs.iter().enumerate() {
+    //let block_nr = nr / self.size;
+    //let block_offset = nr - (block_nr * self.size);
+    //flattened.push(self.blocks[block_nr][block_offset]);
+    //}
+    //flattened
+    //}
+
+    //fn flatten_rows(&self) -> Vec<usize> {
+    //let mut flattened = Vec::with_capacity(self.num_fields);
+    //for row in self.rows.iter() {
+    //for val in row {
+    //flattened.push(*val);
+    //}
+    //}
+    //flattened
+    //}
+
+    //fn flatten_cols(&self) -> Vec<usize> {
+    //let mut flattened = Vec::with_capacity(self.num_fields);
+    //for idx in 0..self.num_fields {
+    //flattened.push(self.cols[idx % self.size][idx / self.size]);
+    //}
+    //flattened
+    //}
 }
 
 fn run() -> Result<(), String> {