d17p1

day17/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day17"
+version = "0.1.0"

day17/Cargo.toml

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+[package]
+name = "day17"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

day17/src/main.rs

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+use std::io;
+use std::env;
+use std::fs::File;
+use std::io::BufReader;
+use std::io::BufRead;
+use std::fmt::Debug;
+
+#[derive(Debug)]
+struct Shape {
+    bot: [i8; 4], // distance from datum. -1 for unused.
+    top: [i8; 4],
+    left: [i8; 4],
+    right: [i8; 4],
+    width: usize,
+    height: usize,
+}
+
+// a Shape's datum is its bottom left corner
+#[derive(Debug)]
+struct Pos {y: usize, x: usize}
+
+static SHAPE_NAMES: [char; 5] = ['-', '+', 'L', '|', '.'];
+static SHAPES: [Shape; 5] = [
+    Shape { // -
+        bot: [0, 0, 0, 0], top: [0, 0, 0, 0],
+        left: [0, -1, -1, -1], right: [3, -1, -1, -1],
+        width: 4, height: 1,
+    },
+    Shape { // +
+        bot: [1, 0, 1, -1], top: [1, 2, 1, -1],
+        left: [1, 0, 1, -1], right: [1, 2, 1, -1],
+        width: 3, height: 3,
+    },
+    Shape { // backward L
+        bot: [0, 0, 0, -1], top: [0, 0, 2, -1],
+        left: [0, 2, 2, -1], right: [2, 2, 2, -1],
+        width: 3, height: 3,
+    },
+    Shape { // |
+        bot: [0, -1, -1, -1], top: [0, -1, -1, -1],
+        left: [0, 0, 0, 0], right: [0, 0, 0, 0],
+        width: 1, height: 4,
+    },
+    Shape { // square
+        bot: [0, 0, -1, -1], top: [1, 1, -1, -1],
+        left: [0, 0, -1, -1], right: [1, 1, -1, -1],
+        width: 2, height: 2,
+    },
+];
+
+fn iterate(
+        map: &mut Vec<[u8; 7]>, shape: &Shape, pos: &mut Pos, wind: u8
+) -> bool {
+    //println!("  __ {}, start {:?}", wind as char, pos);
+    // Wind move
+    match wind {
+        b'>' => 'rightmove: {
+            if pos.x + shape.width == 7 { break 'rightmove; }
+            let mut i = 0;
+            while i < 4 && shape.right[i] >= 0 {
+                let right_point = pos.x + shape.right[i] as usize;
+                if right_point + 1 == 7 { break 'rightmove; }
+                if map[pos.y + i][right_point + 1] != 0 { break 'rightmove; }
+                i += 1;
+            }
+            pos.x += 1;
+            //println!("  >> {:?}", pos);
+        },
+        b'<' => 'leftmove: {
+            if pos.x == 0 { break 'leftmove; }
+            let mut i = 0;
+            while i < 4 && shape.left[i] >= 0 {
+                let left_point = pos.x + shape.left[i] as usize;
+                if left_point == 0 { break 'leftmove; }
+                if map[pos.y + i][left_point - 1] != 0 { break 'leftmove; }
+                i += 1;
+            }
+            pos.x -= 1;
+            //println!("  << {:?}", pos);
+        },
+        _ => panic!(),
+    }
+
+    // Gravity move
+    'downmove: {
+        let mut i = 0;
+        while i < 4 && shape.bot[i] >= 0 {
+            let bot_point = pos.y + shape.bot[i] as usize;
+            if bot_point == 0 { break 'downmove; }
+            if map[bot_point - 1][pos.x + i] != 0 { break 'downmove; }
+            i += 1;
+        }
+        pos.y -= 1;
+        //println!("  vv {:?}", pos);
+        return false;
+    }
+
+    // Settling
+    let mut i = 0;
+    while i < 4 && shape.left[i] >= 0 && shape.right[i] >= 0 {
+        map[pos.y + i][pos.x + shape.left[i] as usize] = 1;
+        map[pos.y + i][pos.x + shape.right[i] as usize] = 1;
+        i += 1;
+    }
+    i = 0;
+    while i < 4 && shape.top[i] >= 0 && shape.bot[i] >= 0 {
+        map[pos.y + shape.top[i] as usize][pos.x + i] = 1;
+        map[pos.y + shape.bot[i] as usize][pos.x + i] = 1;
+        i += 1;
+    }
+    return true;
+}
+
+fn main() -> io::Result<()> {
+    let input_fname = env::args().nth(1).expect("need input file");
+    let mut winds: Vec<u8> = Vec::new();
+    let _ = BufReader::new(File::open(input_fname)?).read_until(b'\n', &mut winds);
+    if winds.last() == Some(&b'\n') { winds.pop(); }
+
+    let mut shape_id = 0;
+    let mut shape = &SHAPES[shape_id];
+    let mut current_top = 0;
+    let mut shape_pos = Pos{x: 2, y: 3};
+    let mut map: Vec<[u8; 7]> = vec![
+        [0, 0, 0, 0, 0, 0, 0],
+        [0, 0, 0, 0, 0, 0, 0],
+        [0, 0, 0, 0, 0, 0, 0],
+        [0, 0, 0, 0, 0, 0, 0],
+    ];
+    prettyprint(&map, &shape_pos, SHAPE_NAMES[shape_id]);
+
+    let mut nrocks = 0;
+    let mut i = 0;
+    while nrocks < 2022 { //debug
+        let c = winds[i % winds.len()];
+        i += 1;
+        if iterate(&mut map, shape, &mut shape_pos, c) {
+            let last_shape_top = shape_pos.y + shape.height - 1;
+            if last_shape_top > current_top {
+                current_top = last_shape_top;
+            }
+            shape_id = (shape_id + 1) % SHAPES.len(); // next shape
+            shape = &SHAPES[shape_id];
+            //println!("{} -> {}", map.len(), last_shape_top + 4 + shape.height);
+            for _ in map.len()..(current_top + 4 + shape.height) {
+                map.push([0, 0, 0, 0, 0, 0, 0]);
+            }
+            nrocks += 1;
+            shape_pos = Pos{x:2, y: current_top + 4};
+            //println!("= {} ({})", current_top, nrocks);
+            prettyprint(&map, &shape_pos, SHAPE_NAMES[shape_id]);
+        }
+    }
+    println!("height = {}", current_top + 1);
+    Ok(())
+}
+
+fn prettyprint(map: &Vec<[u8; 7]>, pos: &Pos, shape_name: char) {
+//     let mut i = map.len();
+//     for row in map.into_iter().rev() {
+//         i -= 1;
+//         print!("|");
+//         for j in 0..7 {
+//             print!("{}", if row[j] == 0 { "." } else { "#" });
+//         }
+//         println!("| {} {}", i, if i == pos.y {shape_name} else {' '});
+//     }
+}

day17/test.txt

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+>>><<><>><<<>><>>><<<>>><<<><<<>><>><<>>