2021: day04: do win check when marking number
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@ -36,7 +36,7 @@ fn part1(input: &str) -> Result<u64> {
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'draw_loop: for draw in draws {
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for grid in &mut grids {
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if grid.mark(draw) && grid.is_winning() {
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if grid.mark(draw) {
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wgrid = Some(grid.clone());
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wdraw = Some(draw);
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break 'draw_loop;
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@ -77,7 +77,7 @@ fn part2(input: &str) -> Result<u64> {
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let mut i = 0;
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while i < grids.len() {
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let grid = &mut grids[i];
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if grid.mark(draw) && grid.is_winning() {
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if grid.mark(draw) {
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grids.remove(i);
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} else {
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i += 1;
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@ -88,7 +88,7 @@ fn part2(input: &str) -> Result<u64> {
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let last_grid = &mut grids[0];
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for draw in draws {
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if last_grid.mark(draw) && last_grid.is_winning() {
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if last_grid.mark(draw) {
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return Ok(draw as u64 * last_grid.unmarked_numbers().map(|n| *n as u64).sum::<u64>());
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}
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}
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@ -101,6 +101,8 @@ struct Grid {
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number_to_pos: HashMap<u8, (usize, usize)>,
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pos_to_number: HashMap<(usize, usize), u8>,
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grid: [bool; GRID_SIZE],
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rows: [u8; GRID_HEIGHT],
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cols: [u8; GRID_WIDTH],
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}
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impl Grid {
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@ -108,32 +110,16 @@ impl Grid {
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match self.number_to_pos.get(&draw) {
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Some(&(x, y)) => {
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*self.access_grid_mut(x, y) = true;
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true
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self.rows[y] += 1;
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self.cols[x] += 1;
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self.rows[y] as usize == GRID_WIDTH || self.cols[x] as usize == GRID_HEIGHT
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}
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None => false,
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}
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}
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fn is_winning(&self) -> bool {
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let mut rows = [0u8; GRID_HEIGHT];
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let mut cols = [0u8; GRID_WIDTH];
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for (y, row) in rows.iter_mut().enumerate() {
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for (x, col) in cols.iter_mut().enumerate() {
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if self.access_grid(x, y) {
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*row += 1;
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*col += 1;
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if *row as usize == GRID_WIDTH || *col as usize == GRID_HEIGHT {
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return true;
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}
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}
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}
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}
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false
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}
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fn unmarked_numbers(&self) -> impl Iterator<Item = &u8> {
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self.number_to_pos
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.iter()
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@ -173,6 +159,8 @@ impl std::str::FromStr for Grid {
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number_to_pos,
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pos_to_number,
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grid: [false; GRID_SIZE],
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rows: [0; GRID_HEIGHT],
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cols: [0; GRID_WIDTH],
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})
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}
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}
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