faster

Cargo.lock

@@ -1,6 +1,7 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "sudk"
 version = "0.1.0"
-

src/main.rs

@@ -1,50 +1,58 @@
-use std::time::Duration;
-
-type Pos = usize;
-
 struct SField {
     field: Vec<usize>,
     fixed: Vec<usize>,
-    known: Vec<usize>,
     size: usize,
     block_size: usize,
-    pos: Pos,
+    pos: usize,
-    pos_last_placed: Pos,
+    pos_last_placed: usize,
     num_fields: usize,
+    possible_values: Vec<Vec<usize>>,
 }
 
 impl SField {
     pub fn new(block_size: usize) -> SField {
         let size = block_size * block_size;
-        //let field = vec![0; size * size];
 
-        /*
+        // EMPTY FIELD
-        let field = vec![0,15,0,0,0,0,11,4,0,5,0,0,0,0,12,8,
+        // let field = vec![0; size * size];
-                        12,0,0,9,0,1,0,5,0,0,8,15,0,0,0,13,
+
-                        0,0,3,0,0,10,13,0,0,11,4,0,15,0,6,0,
+        // BLOCK_SIZE 4
-                        13,10,0,11,0,0,0,14,0,3,2,0,0,9,0,0,
+        // #[rustfmt::skip]
-                        0,0,15,10,8,0,0,0,0,0,14,0,0,6,2,0,
+        // let field = vec![
-                        0,0,14,0,0,0,6,0,0,0,0,0,1,0,0,0,
+        //     0,15,0,0,0,0,11,4,0,5,0,0,0,0,12,8,
-                        0,11,0,8,3,0,15,1,6,0,0,0,0,0,0,7,
+        //     12,0,0,9,0,1,0,5,0,0,8,15,0,0,0,13,
-                        0,6,0,7,0,0,0,0,8,13,0,0,10,0,0,0,
+        //     0,0,3,0,0,10,13,0,0,11,4,0,15,0,6,0,
-                        0,14,0,2,0,0,0,0,3,0,5,0,11,15,9,0,
+        //     13,10,0,11,0,0,0,14,0,3,2,0,0,9,0,0,
-                        0,0,0,12,11,0,2,0,0,0,0,0,0,0,0,0,
+        //     0,0,15,10,8,0,0,0,0,0,14,0,0,6,2,0,
-                        0,8,0,0,6,14,1,0,13,15,0,0,0,0,0,10,
+        //     0,0,14,0,0,0,6,0,0,0,0,0,1,0,0,0,
-                        10,0,0,3,9,0,7,0,0,1,0,0,13,12,8,0,
+        //     0,11,0,8,3,0,15,1,6,0,0,0,0,0,0,7,
-                        7,0,0,0,0,0,14,0,0,0,0,0,0,0,0,9,
+        //     0,6,0,7,0,0,0,0,8,13,0,0,10,0,0,0,
-                        0,3,0,14,0,0,9,6,0,0,0,0,0,4,0,0,
+        //     0,14,0,2,0,0,0,0,3,0,5,0,11,15,9,0,
-                        0,4,6,0,0,7,0,0,0,0,0,0,0,0,0,0,
+        //     0,0,0,12,11,0,2,0,0,0,0,0,0,0,0,0,
-                        5,2,0,0,0,4,10,15,1,0,3,0,0,0,7,0,];
+        //     0,8,0,0,6,14,1,0,13,15,0,0,0,0,0,10,
-        */
+        //     10,0,0,3,9,0,7,0,0,1,0,0,13,12,8,0,
+        //     7,0,0,0,0,0,14,0,0,0,0,0,0,0,0,9,
+        //     0,3,0,14,0,0,9,6,0,0,0,0,0,4,0,0,
+        //     0,4,6,0,0,7,0,0,0,0,0,0,0,0,0,0,
+        //     5,2,0,0,0,4,10,15,1,0,3,0,0,0,7,0,
+        // ];
 
         // MANY SOLUTIONS
+        #[rustfmt::skip]
         let field = vec![
-            0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 8, 9, 0, 2, 0, 0, 0, 0, 0, 2, 0, 4, 0, 0, 0, 0,
+            0,0,0,0,0,0,0,0,9,
-            4, 0, 6, 0, 0, 0, 8, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 6, 5, 0, 0, 2, 0, 7, 4, 0, 3, 0, 0,
+            0,0,0,0,8,9,0,2,0,
-            0, 5, 0, 4, 0, 0, 0, 1, 8, 0, 0, 0, 0, 0, 0, 0, 8, 2, 0, 0, 0, 6, 0,
+            0,0,0,0,2,0,4,0,0,
+            0,0,4,0,6,0,0,0,8,
+            0,0,0,5,0,0,0,0,0,
+            0,6,5,0,0,2,0,7,4,
+            0,3,0,0,0,5,0,4,0,
+            0,0,1,8,0,0,0,0,0,
+            0,0,8,2,0,0,0,6,0,
         ];
 
         // HARD
+        // #[rustfmt::skip]
         // let field = vec![
         //     8,4,0,0,6,0,5,0,1,
         //     0,0,0,0,0,3,0,4,0,
@@ -58,6 +66,7 @@ impl SField {
         // ];
 
         // EASY
+        // #[rustfmt::skip]
         // let field = vec![
         //     5,9,0,6,1,3,0,0,0,
         //     0,0,0,9,0,0,5,0,0,
@@ -79,52 +88,60 @@ impl SField {
             }
         });
 
-        let mut known = Vec::with_capacity(size * size);
-        field.iter().for_each(|e| {
-            if *e == 0 {
-                known.push(0);
-            } else {
-                known.push(1);
-            }
-        });
-
         SField {
             field,
             fixed,
-            known,
             size,
             block_size,
             pos: 0,
             pos_last_placed: 0,
             num_fields: size * size,
+            possible_values: vec![vec![]; size * size],
         }
     }
 
+    fn build_possible_values_db(&mut self) {
+        for idx in 0..self.num_fields {
+            if self.fixed[idx] == 1 {
+                continue;
+            }
+            self.pos = idx;
+            // try all values between 1 and =self.size and remember the good ones
+            let mut good_ones = Vec::with_capacity(self.size);
+            for nr in 1..=self.size {
+                if self.ok(nr) {
+                    good_ones.push(nr);
+                }
+            }
+            self.possible_values[idx] = good_ones;
+        }
+        self.pos = 0;
+    }
+
     pub fn solve_backtracking(&mut self) -> bool {
         let mut found_solution = false;
         let mut num_solutions = 0;
 
+        //let mut loop_count = 0;
         loop {
-            //println!("loop start");
+            //std::thread::sleep_ms(30);
-            //println!("==========================");
-            //std::thread::sleep(Duration::from_millis(100));
             //self.print_clear();
-            //println!("pos:{}", self.pos);
             //self.print();
+            //loop_count += 1;
+            //if loop_count % 1000000 == 0 {
+            //self.print_clear();
+            //self.print();
+            //}
             if self.is_end() {
-                //println!("is_end");
                 found_solution = true;
                 num_solutions += 1;
                 if num_solutions % 100 == 0 {
                     self.print_clear();
                     println!("Solutions: {}", num_solutions);
                     self.print();
-                    // std::thread::sleep(Duration::from_millis(1000));
                 }
-                //std::thread::sleep(Duration::from_secs(2));
 
                 if self.is_fixed() {
-                    // println!("is end is fixed");
                     continue;
                 }
                 self.clear_current_field();
@@ -133,25 +150,22 @@ impl SField {
             }
 
             if self.is_fixed() {
-                // println!("is fixed -> next");
                 self.next();
                 continue;
             }
 
             if self.goto_next_free_field() {
-                // println!("goto_next_free_field");
                 if self.put_valid_nr() {
-                    // println!("placed valid nr");
                     self.next();
                     continue;
                 } else {
-                    // println!("could not place valid nr...going back");
+                    //println!("put_valid_nr failed for pos {}", self.pos);
+                    //std::thread::sleep_ms(300);
                     self.clear_current_field();
                     if !self.prev() {
                         println!("Number of solutions: {}", num_solutions);
                         break;
                     }
-                    //println!("{} {}", self.pos.row, self.pos.col);
                     if !self.goto_prev_free_field() {
                         println!("Number of solutions: {}", num_solutions);
                         break;
@@ -203,7 +217,7 @@ impl SField {
                 self.print_gray();
             }
 
-            print!("{} ", self.get_field_at_pos(i));
+            print!("{:2} ", self.get_field_at_pos(i));
 
             if i == self.pos || i == self.pos_last_placed || self.get_field_at_pos(i) == 0 {
                 self.print_neutral();
@@ -217,6 +231,7 @@ impl SField {
         self.set(0);
     }
 
+    #[inline(always)]
     fn goto_prev_free_field(&mut self) -> bool {
         while {
             if !self.is_fixed() {
@@ -228,6 +243,7 @@ impl SField {
         false
     }
 
+    #[inline(always)]
     fn goto_next_free_field(&mut self) -> bool {
         while {
             if !self.is_fixed() {
@@ -239,22 +255,34 @@ impl SField {
         false
     }
 
-    fn goto_next_free_field_not_known(&mut self) -> bool {
+    #[inline(always)]
-        while {
+    fn _put_valid_nr(&mut self) -> bool {
-            if !self.is_fixed() && !self.is_known() {
+        let current_nr = self.get_field_at_pos(self.pos);
+
+        for nr in current_nr..self.size + 1 {
+            if self.ok(nr) {
+                self.set(nr);
                 return true;
             }
-            self.next()
+        }
-        } {}
 
         false
     }
 
+    #[inline(always)]
     fn put_valid_nr(&mut self) -> bool {
         let current_nr = self.get_field_at_pos(self.pos);
-        for nr in current_nr..self.size + 1 {
+
-            if self.ok(nr) {
+        let possible_vals = unsafe { self.possible_values.get_unchecked(self.pos) };
-                self.set(nr);
+
+        for idx in 0..possible_vals.len() {
+            let nr = unsafe { possible_vals.get_unchecked(idx) };
+            if *nr <= current_nr {
+                continue;
+            }
+
+            if self.ok(*nr) {
+                self.set(*nr);
                 return true;
             }
         }
@@ -271,84 +299,75 @@ impl SField {
         self.block_ok(nr) && self.row_ok(nr) && self.col_ok(nr)
     }
 
+    #[inline(always)]
+    fn _pos_to_xy(&self) -> (usize, usize) {
+        let y = self.pos / self.size;
+        let x = self.pos % self.size;
+        (x + 1, y + 1)
+    }
+
     #[inline(always)]
     fn is_fixed(&self) -> bool {
         unsafe { *self.fixed.get_unchecked(self.pos) == 1 }
     }
 
     #[inline(always)]
-    fn is_known(&self) -> bool {
+    fn get_field_at_pos(&self, pos: usize) -> usize {
-        unsafe { *self.known.get_unchecked(self.pos) == 1 }
-    }
-
-    #[inline(always)]
-    fn get_field_at_pos(&self, pos: Pos) -> usize {
         unsafe { *self.field.get_unchecked(pos) }
     }
 
     #[inline(always)]
     fn set(&mut self, nr: usize) {
-        assert!(!self.is_fixed());
         self.field[self.pos] = nr;
         self.pos_last_placed = self.pos;
     }
 
     #[inline(always)]
-    fn set_with_known(&mut self, nr: usize) {
+    fn get_row(&self, row: &mut [usize; 9]) {
-        assert!(!self.is_fixed());
+        for (idx, row_elem) in row.iter_mut().enumerate() {
-        self.field[self.pos] = nr;
+            *row_elem = self.get_field_at_pos((self.pos / self.size) * self.size + idx);
-        self.known[self.pos] = 1;
-        self.pos_last_placed = self.pos;
-    }
-
-    #[inline(always)]
-    fn get_row(&self) -> Vec<usize> {
-        let mut row = Vec::with_capacity(self.size);
-        for val in 0..self.size {
-            row.push(self.get_field_at_pos((self.pos / self.size) * self.size + val));
         }
-        row
     }
 
     #[inline(always)]
-    fn get_col(&self) -> Vec<usize> {
+    fn get_col(&self, col: &mut [usize; 9]) {
-        let mut col = Vec::with_capacity(self.size);
+        for (idx, col_elem) in col.iter_mut().enumerate() {
-        for val in 0..self.size {
+            *col_elem = self.get_field_at_pos(idx * self.size + self.pos % self.size);
-            col.push(self.get_field_at_pos(val * self.size + self.pos % self.size));
         }
-        col
     }
 
     #[inline(always)]
-    fn get_block(&self) -> Vec<usize> {
+    fn get_block(&self, block: &mut [usize; 9]) {
-        let mut block = Vec::with_capacity(self.size);
-
         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;
 
         for r in 0..self.block_size {
             for c in 0..self.block_size {
-                block.push(
+                block[r * self.block_size + c] =
-                    self.get_field_at_pos(self.size * (block_start_row + r) + block_start_col + c),
+                    self.get_field_at_pos(self.size * (block_start_row + r) + block_start_col + c);
-                );
             }
         }
-        block
     }
 
     #[inline(always)]
     fn block_ok(&self, nr: usize) -> bool {
-        !self.get_block().contains(&nr)
+        let mut block = [0; 9];
+        self.get_block(&mut block);
+        !block.contains(&nr)
     }
 
     #[inline(always)]
     fn row_ok(&self, nr: usize) -> bool {
-        !self.get_row().contains(&nr)
+        let mut row = [0; 9];
+        self.get_row(&mut row);
+        !row.contains(&nr)
     }
 
     #[inline(always)]
     fn col_ok(&self, nr: usize) -> bool {
-        !self.get_col().contains(&nr)
+        let mut col = [0; 9];
+        self.get_col(&mut col);
+        !col.contains(&nr)
     }
 
     #[inline(always)]
@@ -371,115 +390,20 @@ impl SField {
         true
     }
 
-    fn get_block_nums(&mut self) -> u16 {
+    #[inline(always)]
-        let mut result = 0u16;
+    fn solve(&mut self) {
-
-        for num in self.get_block().into_iter() {
-            if num > 0 {
-                result |= 1 << (num - 1);
-            }
-        }
-
-        // println!("blk: {} {:016b}", self.pos, result);
-        result
-    }
-
-    fn get_col_nums(&mut self) -> u16 {
-        let mut result = 0u16;
-
-        for num in self.get_col().into_iter() {
-            if num > 0 {
-                result |= 1 << (num - 1);
-            }
-        }
-
-        // println!("col: {} {:016b}", self.pos, result);
-        result
-    }
-
-    fn get_row_nums(&mut self) -> u16 {
-        let mut result = 0u16;
-
-        for num in self.get_row().into_iter() {
-            if num > 0 {
-                result |= 1 << (num - 1);
-            }
-        }
-
-        // println!("row: {} {:016b}", self.pos, result);
-        result
-    }
-
-    fn place_nr_by_deduction_if_possible(&mut self) -> bool {
-        let combined = self.get_row_nums() | self.get_col_nums() | self.get_block_nums();
-
-        let ones = combined.count_ones();
-        assert!(ones < 9); // should never have 9 ones because the field wouldn't be empty in the first place
-
-        if ones == 8 {
-            let nr = combined.trailing_ones() + 1;
-            self.set_with_known(nr as usize);
-            // println!("Placing nr: {} at pos: {}", nr, self.pos);
-            return true;
-        }
-
-        false
-    }
-
-    fn solve_deduction(&mut self) -> bool {
-        return false;
-
-        let mut was_able_to_place_nr = false;
-
-        loop {
-            if self.goto_next_free_field_not_known() {
-                was_able_to_place_nr |= self.place_nr_by_deduction_if_possible();
-
-                if !self.next() {
-                    if was_able_to_place_nr {
-                        self.pos = 0;
-                        was_able_to_place_nr = false;
-                    } else {
-                        self.pos = 0;
-                        return self.is_end();
-                    }
-                }
-            } else {
-                if was_able_to_place_nr {
-                    self.pos = 0;
-                    was_able_to_place_nr = false;
-                } else {
-                    self.pos = 0;
-                    return self.is_end();
-                }
-            }
-        }
-    }
-
-    fn solve(&mut self) -> bool {
-        //loop {
-        //if self.solve_deduction() {
-        //break;
-        //} else {
-        self.pos = 0;
-        println!("Falling back to backtracking");
         if !self.solve_backtracking() {
             println!("there is no solution.");
-            return false;
         }
-        //}
-        //}
-
-        self.print();
-        true
     }
 }
 
 fn run() -> Result<(), String> {
     let mut field = SField::new(3);
 
+    field.build_possible_values_db();
+
     field.solve();
-    //field.get_row_missing_numbers(&Pos{row:4, col:5});
     Ok(())
 }