Several more working days

2016/day13/Cargo.lock

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+[root]
+name = "day13"
+version = "0.1.0"
+

2016/day13/Cargo.toml

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+[package]
+name = "day13"
+version = "0.1.0"
+authors = ["~krowbar"]
+
+[dependencies]

2016/day13/src/main.rs

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+#[derive(Debug)]
+enum Space {
+    Wall,
+    Open,
+}
+
+fn get_space(x: u32, y: u32, favorite_number: u32) -> Space {
+    let total: u32 = x*x + 3*x + 2*x*y + y + y*y + favorite_number;
+    //println!("{}, {}", total, total.count_ones());
+    if total.count_ones() % 2 == 0 { /*even*/
+        Space::Open
+    }
+    else { /*odd*/
+        Space::Wall
+    }
+}
+
+// fn print_maze(width: u32, height: u32, key: u32) {
+//     //print header
+//     print!("  ");
+//     for col in 0..width {
+//         print!("{}", col % 10);
+//     }
+//     println!("");
+//     for row in 0..height {
+//         print!("{} ", row % 10);
+//         for col in 0..width {
+//             match get_space(col, row, key) {
+//                 Space::Wall => print!("#"),
+//                 Space::Open => print!("."),
+//             }
+//         }
+//         println!("");
+//     }
+// }
+
+const MAZE_WIDTH: usize = 40;
+const MAZE_HEIGHT: usize = 50;
+const MAX_STEPS: u32 = 50;
+static mut COUNT: u32 = 0;
+
+fn build_maze(maze: &mut Vec<Vec<(bool, u32)>>, key: u32) {
+    for row in 0..MAZE_HEIGHT {
+        for col in 0..MAZE_WIDTH {
+            match get_space(col as u32, row as u32, key) {
+                Space::Open => maze[row][col] = (true, u32::max_value()),
+                Space::Wall => maze[row][col] = (false, 0),
+            }
+        }
+    }
+}
+
+fn walk_maze(maze: &mut Vec<Vec<(bool, u32)>>, pos: (usize, usize), step: u32) {
+    if maze[pos.0][pos.1].0 == false /* if position is a wall */
+        || step >= maze[pos.0][pos.1].1 /* or position has a better step value */ {
+        return; // abort now
+    }
+    // otherwise
+    // if this space is within MAX_STEPS and hasn't yet been counted
+    if maze[pos.0][pos.1].1 == u32::max_value() { //if we never visited this space before
+        if step <= MAX_STEPS {
+            unsafe {
+                COUNT = COUNT + 1;
+            }
+        }
+    }
+    else if maze[pos.0][pos.1].1 > MAX_STEPS && step <= MAX_STEPS {
+        unsafe {
+            COUNT = COUNT + 1;
+        }
+    }
+
+    // set the step value
+    maze[pos.0][pos.1].1 = step;
+
+    //check left
+    if pos.1 > 0 {
+        walk_maze(maze, (pos.0, pos.1-1), step+1);
+    }
+
+    //check right
+    if pos.1 + 1 < MAZE_WIDTH {
+        walk_maze(maze, (pos.0, pos.1+1), step+1);
+    }
+
+    //check up
+    if pos.0 > 0 {
+        walk_maze(maze, (pos.0-1, pos.1), step+1);
+    }
+
+    //check down
+    if pos.0 + 1 < MAZE_HEIGHT {
+        walk_maze(maze, (pos.0+1, pos.1), step+1);
+    }
+}
+
+fn print_maze(maze: &Vec<Vec<(bool, u32)>>) {
+    print!("    "); //first row padding
+    for col in 0..MAZE_WIDTH {
+        print!("{:02} ", col % 100);
+    }
+    println!(""); //newline
+    for row in 0..MAZE_HEIGHT {
+        print!("{:02}: ", row % 100);
+        for col in 0..MAZE_WIDTH {
+            if maze[row][col].0 == true {
+                if maze[row][col].1 == u32::max_value() {
+                    print!(".. "); //unpassable
+                }
+                else {
+                    print!("{:02} ", maze[row][col].1 % 100); //step value
+                }
+            }
+            else {
+                print!("## "); //it's a wall
+            }
+        }
+        println!(""); //print the new line
+    }
+}
+
+fn main() {
+    //let mut pos = (1, 1);
+    //let goal = (31, 39);
+
+    //println!("Answer is {:?}", get_space(1, 2, 3));
+    let mut maze: Vec<Vec<(bool, u32)>> = vec![vec![(false, 0); MAZE_WIDTH]; MAZE_HEIGHT];
+    //print_maze(32, 40, 1358);
+    build_maze(&mut maze, 1358);
+    walk_maze(&mut maze, (1, 1), 0);
+    //print_maze(&maze);
+    let end = (31, 39);
+    println!("Part 1: It takes {} steps to get to ({}, {})", maze[end.1][end.0].1, end.0, end.1);
+    unsafe {
+        println!("Part 2: There are {} positions within {} steps", COUNT, MAX_STEPS);
+    }
+}