rust version: backtracking simplified and other improvements
* backtracking: main loop simplified * instead of the `fixed` Vec, we now use skip fields to calculate how many fields to skip in `next()` and `prev()`. This is faster because we get rid of the `if` statement thus no branching occurs.
This commit is contained in:
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198084206b
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GPG Key ID:
3841F1C27E6F0E14
@ -1,3 +1,2 @@
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[build]
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target = "x86_64-unknown-linux-musl"
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rustflags = "-C target-cpu=native -C strip=symbols"
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rustflags = ["-C", "target-cpu=native", "-C", "target-feature=+crt-static"]
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@ -9,5 +9,6 @@ edition = "2021"
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[profile.release]
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lto = true
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debug = false
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codegen-units = 1
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strip = true
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panic = "abort"
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codegen-units = 1
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414
flamegraph.svg
Normal file
414
flamegraph.svg
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File diff suppressed because one or more lines are too long
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After Width: | Height: | Size: 35 KiB |
350
src/main.rs
350
src/main.rs
@ -2,120 +2,89 @@ use std::time::Instant;
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const BLOCK_SIZE: usize = 3;
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const SIZE: usize = BLOCK_SIZE * BLOCK_SIZE;
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const NUM_FIELDS: usize = SIZE * SIZE;
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struct SField {
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field: Vec<u8>,
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fixed: Vec<bool>,
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size: usize,
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block_size: usize,
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skipf: Vec<u8>,
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skipb: Vec<u8>,
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pos: usize,
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pos_last_placed: usize,
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num_fields: usize,
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possible_values: Vec<Vec<u8>>,
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}
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/// Some test fields:
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///
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/// EMPTY FIELD
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/// let field = vec![0; SIZE * SIZE];
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///
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/// MANY SOLUTIONS
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/// #[rustfmt::skip]
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/// let field = vec![
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/// 0,0,0,0,0,0,0,0,9,
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/// 0,0,0,0,8,9,0,2,0,
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/// 0,0,0,0,2,0,4,0,0,
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/// 0,0,4,0,6,0,0,0,8,
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/// 0,0,0,5,0,0,0,0,0,
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/// 0,6,5,0,0,2,0,7,4,
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/// 0,3,0,0,0,5,0,4,0,
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/// 0,0,1,8,0,0,0,0,0,
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/// 0,0,8,2,0,0,0,6,0,
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/// ];
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///
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/// HARD
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/// #[rustfmt::skip]
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/// let field = vec![
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/// 8,4,0,0,6,0,5,0,1,
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/// 0,0,0,0,0,3,0,4,0,
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/// 0,0,6,9,0,0,0,0,7,
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/// 0,2,0,7,1,0,0,0,6,
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/// 0,0,0,6,3,0,0,0,0,
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/// 9,0,0,0,0,0,0,5,0,
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/// 0,0,0,0,4,0,0,6,0,
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/// 2,0,0,0,0,0,1,8,0,
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/// 0,0,5,0,0,0,3,0,0,
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/// ];
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///
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/// EASY
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/// #[rustfmt::skip]
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/// let field = vec![
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/// 5,9,0,6,1,3,0,0,0,
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/// 0,0,0,9,0,0,5,0,0,
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/// 8,0,3,0,5,7,6,4,0,
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/// 0,7,5,0,0,0,4,0,6,
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/// 0,6,0,7,4,0,2,0,8,
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/// 2,0,8,0,0,0,7,5,3,
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/// 0,0,0,5,6,1,0,7,0,
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/// 0,0,1,0,7,0,9,0,0,
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/// 7,3,6,0,2,0,0,0,0,
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/// ];
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///
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/// // BLOCK_SIZE 4 MANY SOLUTIONS (DOESN'T FINISH)
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/// #[rustfmt::skip]
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/// let field = vec![
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/// 0,15,0,0,0,0,11,4,0,5,0,0,0,0,12,8,
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/// 12,0,0,9,0,1,0,5,0,0,8,15,0,0,0,13,
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/// 0,0,3,0,0,10,13,0,0,11,4,0,15,0,6,0,
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/// 13,10,0,11,0,0,0,14,0,3,2,0,0,9,0,0,
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/// 0,0,15,10,8,0,0,0,0,0,14,0,0,6,2,0,
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/// 0,0,14,0,0,0,6,0,0,0,0,0,1,0,0,0,
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/// 0,11,0,8,3,0,15,1,6,0,0,0,0,0,0,7,
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/// 0,6,0,7,0,0,0,0,8,13,0,0,10,0,0,0,
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/// 0,14,0,2,0,0,0,0,3,0,5,0,11,15,9,0,
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/// 0,0,0,12,11,0,2,0,0,0,0,0,0,0,0,0,
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/// 0,8,0,0,6,14,1,0,13,15,0,0,0,0,0,10,
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/// 10,0,0,3,9,0,7,0,0,1,0,0,13,12,8,0,
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/// 7,0,0,0,0,0,14,0,0,0,0,0,0,0,0,9,
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/// 0,3,0,14,0,0,9,6,0,0,0,0,0,4,0,0,
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/// 0,4,6,0,0,7,0,0,0,0,0,0,0,0,0,0,
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/// 5,2,0,0,0,4,10,15,1,0,3,0,0,0,7,0,
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/// ];
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impl SField {
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pub fn new() -> SField {
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let field = vec![0; SIZE * SIZE];
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#[rustfmt::skip]
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let field = vec![
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0,0,0,0,0,0,0,0,0,
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0,0,0,0,8,9,0,0,0,
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0,0,0,0,2,0,4,0,0,
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0,0,4,0,6,0,0,0,8,
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0,0,0,5,0,0,0,0,0,
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0,6,5,0,0,2,0,7,4,
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0,3,0,0,0,5,0,4,0,
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0,0,1,8,0,0,0,0,0,
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0,0,8,2,0,0,0,6,0,
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];
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let mut fixed = Vec::with_capacity(SIZE * SIZE);
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field.iter().for_each(|e| {
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if *e == 0 {
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fixed.push(false);
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} else {
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fixed.push(true);
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fn find_fixed_streak_forward(mut idx: usize, field: &[u8]) -> u8 {
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let mut fixed_count = 1;
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idx += 1;
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while idx < NUM_FIELDS && field[idx] > 0 {
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fixed_count += 1;
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idx += 1;
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}
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fixed_count
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}
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fn find_fixed_streak_backward(mut idx: usize, field: &[u8]) -> u8 {
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let mut fixed_count = 1;
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idx -= 1;
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while idx < NUM_FIELDS && field[idx] > 0 {
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fixed_count += 1;
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idx -= 1;
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}
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fixed_count
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}
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let mut skipf = vec![0; NUM_FIELDS];
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for (idx, nr) in field.iter().enumerate() {
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match nr {
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0 => skipf[idx] = *nr,
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_ => skipf[idx] = find_fixed_streak_forward(idx, &field),
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}
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}
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let mut skipb = vec![0; NUM_FIELDS];
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for (idx, nr) in field.iter().enumerate().rev() {
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match nr {
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0 => skipb[idx] = *nr,
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_ => skipb[idx] = find_fixed_streak_backward(idx, &field),
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}
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}
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});
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SField {
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field,
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fixed,
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size: SIZE,
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block_size: BLOCK_SIZE,
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skipf,
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skipb,
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pos: 0,
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pos_last_placed: 0,
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num_fields: SIZE * SIZE,
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possible_values: vec![vec![]; SIZE * SIZE],
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}
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}
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fn build_possible_values_db(&mut self) {
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for idx in 0..self.num_fields {
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if self.fixed[idx] {
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for idx in 0..NUM_FIELDS {
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if self.field[idx] != 0 {
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continue;
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}
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self.pos = idx;
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// try all values between 1 and =self.size and remember the good ones
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let mut good_ones = Vec::with_capacity(self.size);
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for nr in 1..=(self.size as u8) {
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let mut good_ones = Vec::with_capacity(SIZE);
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for nr in 1..=(SIZE as u8) {
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if self.ok(nr) {
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good_ones.push(nr);
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}
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@ -126,121 +95,59 @@ impl SField {
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}
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pub fn solve_backtracking(&mut self) -> bool {
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let mut found_solution = false;
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let mut num_solutions = 0;
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let mut last_num_solutions = num_solutions;
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let mut loop_count = 0;
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let mut last_loop_count = loop_count;
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let mut now = Instant::now();
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loop {
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loop_count += 1;
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const MILLIS_PER_SEC: u128 = 1_000;
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const UPDATE_DELAY_MS: u128 = 80;
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if loop_count % 1000 == 0 {
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let elapsed_ms = now.elapsed().as_millis();
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if elapsed_ms <= UPDATE_DELAY_MS {
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continue;
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}
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self.print_clear();
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self.print();
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println!(
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"{} loops/sec",
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(loop_count - last_loop_count) * (MILLIS_PER_SEC / elapsed_ms)
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);
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println!(
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"{} solutions/sec",
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(num_solutions - last_num_solutions) * (MILLIS_PER_SEC / elapsed_ms)
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);
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last_loop_count = loop_count;
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last_num_solutions = num_solutions;
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now = Instant::now();
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}
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if self.is_end() {
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found_solution = true;
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num_solutions += 1;
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/*
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if num_solutions % 100 == 0 {
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self.print_clear();
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println!("Solutions: {}", num_solutions);
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self.print();
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}
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*/
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if self.is_fixed() {
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continue;
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}
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self.clear_current_field();
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self.prev();
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self.goto_prev_free_field();
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}
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if self.is_fixed() {
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self.next();
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continue;
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}
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if self.goto_next_free_field() {
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if self.put_valid_nr() {
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self.next();
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continue;
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} else {
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//println!("put_valid_nr failed for pos {}", self.pos);
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//std::thread::sleep_ms(300);
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if !self.put_valid_nr() {
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self.clear_current_field();
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if !self.prev() {
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self.print_clear();
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self.print();
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println!("Number of solutions: {}", num_solutions);
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break;
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}
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if !self.goto_prev_free_field() {
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continue;
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}
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if !self.next() {
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num_solutions += 1;
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if num_solutions % 10_000 == 0 {
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self.print_clear();
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self.print();
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println!("Number of solutions: {}", num_solutions);
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break;
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}
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}
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self.clear_current_field();
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self.prev();
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}
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}
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found_solution
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num_solutions > 0
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}
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#[inline(always)]
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fn print_gray(&self) {
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print!("\x1b\x5b\x31\x3b\x33\x30\x6d");
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}
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#[inline(always)]
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fn print_green(&self) {
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print!("\x1b\x5b\x31\x3b\x33\x32\x6d");
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}
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#[inline(always)]
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fn print_red(&self) {
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print!("\x1b\x5b\x31\x3b\x33\x31\x6d");
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}
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#[inline(always)]
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fn print_neutral(&self) {
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print!("\x1b\x5b\x31\x3b\x30\x6d");
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}
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#[inline(always)]
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fn print_clear(&self) {
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print!("\x1b\x5b\x48\x1b\x5b\x32\x4a");
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}
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#[inline(always)]
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fn print(&self) {
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for i in 0..self.num_fields {
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if i != 0 && i % self.size == 0 {
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for i in 0..NUM_FIELDS {
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if i != 0 && i % SIZE == 0 {
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println!();
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}
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if i == self.pos_last_placed {
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self.print_red();
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} else if i == self.pos {
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if i == self.pos {
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self.print_green();
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} else if self.get_field_at_pos(i) == 0 {
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self.print_gray();
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@ -248,57 +155,17 @@ impl SField {
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print!("{:2} ", self.get_field_at_pos(i));
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if i == self.pos || i == self.pos_last_placed || self.get_field_at_pos(i) == 0 {
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if i == self.pos || self.get_field_at_pos(i) == 0 {
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self.print_neutral();
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}
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}
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println!();
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}
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#[inline(always)]
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fn clear_current_field(&mut self) {
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self.set(0);
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}
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#[inline(always)]
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fn goto_prev_free_field(&mut self) -> bool {
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while {
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if !self.is_fixed() {
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return true;
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}
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self.prev()
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} {}
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false
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}
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#[inline(always)]
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fn goto_next_free_field(&mut self) -> bool {
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while {
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if !self.is_fixed() {
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return true;
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}
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self.next()
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} {}
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false
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}
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#[inline(always)]
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fn _put_valid_nr(&mut self) -> bool {
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let current_nr = self.get_field_at_pos(self.pos);
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for nr in current_nr..(self.size + 1) as u8 {
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if self.ok(nr) {
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self.set(nr);
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return true;
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}
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}
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false
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}
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#[inline(always)]
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fn put_valid_nr(&mut self) -> bool {
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let current_nr = self.get_field_at_pos(self.pos);
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@ -320,32 +187,10 @@ impl SField {
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false
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}
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#[inline(always)]
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fn is_end(&self) -> bool {
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!self.field.contains(&0)
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}
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#[inline(always)]
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fn ok(&self, nr: u8) -> bool {
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self.block_ok(nr) && self.row_ok(nr) && self.col_ok(nr)
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}
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#[inline(always)]
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fn _pos_to_xy(&self) -> (usize, usize) {
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let y = self.pos / self.size;
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let x = self.pos % self.size;
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(x + 1, y + 1)
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}
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#[inline(always)]
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fn is_fixed(&self) -> bool {
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// safety: self.pos can be used to index the field unchecked
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// since the only methods modifying self.pos are
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// `next()` and `prev()` and they do bounds checking
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unsafe { *self.fixed.get_unchecked(self.pos) }
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}
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#[inline(always)]
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fn get_field_at_pos(&self, pos: usize) -> u8 {
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// safety:
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// TODO
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@ -354,81 +199,74 @@ impl SField {
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unsafe { *self.field.get_unchecked(pos) }
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}
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#[inline(always)]
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fn set(&mut self, nr: u8) {
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self.field[self.pos] = nr;
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self.pos_last_placed = self.pos;
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}
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#[inline(always)]
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fn get_row(&self, row: &mut [u8; SIZE]) {
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for (idx, row_elem) in row.iter_mut().enumerate() {
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*row_elem = self.get_field_at_pos((self.pos / self.size) * self.size + idx);
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*row_elem = self.get_field_at_pos((self.pos / SIZE) * SIZE + idx);
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}
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}
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#[inline(always)]
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fn get_col(&self, col: &mut [u8; SIZE]) {
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for (idx, col_elem) in col.iter_mut().enumerate() {
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*col_elem = self.get_field_at_pos(idx * self.size + self.pos % self.size);
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*col_elem = self.get_field_at_pos(idx * SIZE + self.pos % SIZE);
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}
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}
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#[inline(always)]
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fn get_block(&self, block: &mut [u8; SIZE]) {
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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;
|
||||
let block_start_row = self.pos / SIZE / BLOCK_SIZE * BLOCK_SIZE;
|
||||
let block_start_col = self.pos % SIZE / BLOCK_SIZE * BLOCK_SIZE;
|
||||
|
||||
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);
|
||||
for r in 0..BLOCK_SIZE {
|
||||
for c in 0..BLOCK_SIZE {
|
||||
block[r * BLOCK_SIZE + c] =
|
||||
self.get_field_at_pos(SIZE * (block_start_row + r) + block_start_col + c);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
#[inline(always)]
|
||||
fn block_ok(&self, nr: u8) -> bool {
|
||||
let mut block = [0; SIZE];
|
||||
self.get_block(&mut block);
|
||||
!block.contains(&nr)
|
||||
}
|
||||
|
||||
#[inline(always)]
|
||||
fn row_ok(&self, nr: u8) -> bool {
|
||||
let mut row = [0; SIZE];
|
||||
self.get_row(&mut row);
|
||||
!row.contains(&nr)
|
||||
}
|
||||
|
||||
#[inline(always)]
|
||||
fn col_ok(&self, nr: u8) -> bool {
|
||||
let mut col = [0; SIZE];
|
||||
self.get_col(&mut col);
|
||||
!col.contains(&nr)
|
||||
}
|
||||
|
||||
#[inline(always)]
|
||||
fn next(&mut self) -> bool {
|
||||
if self.pos == self.num_fields - 1 {
|
||||
let new_pos = self.pos + 1 + unsafe { *self.skipf.get_unchecked(self.pos + 1) as usize };
|
||||
|
||||
if new_pos >= NUM_FIELDS {
|
||||
return false;
|
||||
}
|
||||
|
||||
self.pos += 1;
|
||||
self.pos = new_pos;
|
||||
true
|
||||
}
|
||||
|
||||
#[inline(always)]
|
||||
fn prev(&mut self) -> bool {
|
||||
if self.pos == 0 {
|
||||
let new_pos = self.pos - 1 - unsafe { *self.skipb.get_unchecked(self.pos - 1) as usize };
|
||||
|
||||
if new_pos >= NUM_FIELDS {
|
||||
return false;
|
||||
}
|
||||
|
||||
self.pos -= 1;
|
||||
self.pos = new_pos;
|
||||
true
|
||||
}
|
||||
|
||||
#[inline(always)]
|
||||
fn solve(&mut self) {
|
||||
let now = Instant::now();
|
||||
if !self.solve_backtracking() {
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user