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extern crate regex;
use std::io::BufReader;
use std::io::prelude::*;
use std::fs::File;
use std::collections::HashMap;
use std::collections::HashSet;
use regex::Regex;
use std::str::FromStr;
#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq)]
struct Node {
x: i8,
y: i8,
size: i16,
used: i16,
avail: i16,
blocker: bool
}
impl FromStr for Node {
type Err = String;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let reg = Regex::new(r"/dev/grid/node-x(\d+)-y(\d+) +(\d+)T +(\d+)T +(\d+)T +(\d+)%").unwrap();
let cap = match reg.captures(s) {
Some(cap) => cap,
None => return Err("Does not match regex".to_string())
};
Ok(Node {
x: cap.at(1).unwrap().parse().unwrap(),
y: cap.at(2).unwrap().parse().unwrap(),
size: cap.at(3).unwrap().parse().unwrap(),
used: cap.at(4).unwrap().parse().unwrap(),
avail: cap.at(5).unwrap().parse().unwrap(),
blocker: false
})
}
}
impl Node {
fn is_viable_pair(&self, other: &Node) -> bool {
(self.x != other.x || self.y != other.y) && self.used > 0 && self.used <= other.avail
}
fn recalculate_avail(&mut self) {
self.avail = self.size - self.used;
debug_assert!(self.avail >= 0);
debug_assert!(self.used >= 0);
}
}
#[derive(Clone, Hash, PartialEq, Eq)]
struct Grid {
nodes: Vec<Vec<Node>>,
goal_x: i8,
goal_y: i8
}
impl Grid {
fn new(nodes: Vec<Node>) -> Grid {
let mut grid_nodes = Vec::new();
let mut next_col = Vec::new();
let mut current_x = 0;
for node in nodes {
if current_x != node.x {
grid_nodes.push(next_col);
next_col = Vec::new();
current_x += 1;
}
next_col.push(node);
}
grid_nodes.push(next_col);
grid_nodes = Grid::normalize(grid_nodes);
Grid {
nodes: grid_nodes,
goal_x: current_x,
goal_y: 0
}
}
fn normalize(mut nodes: Vec<Vec<Node>>) -> Vec<Vec<Node>> {
for x in 0..nodes.len() {
for y in 0..nodes[x].len() {
nodes[x][y].size = ((nodes[x][y].size + 50)/100) * 100;
nodes[x][y].used = ((nodes[x][y].used + 50)/100) * 100;
nodes[x][y].avail = ((nodes[x][y].avail + 50)/100) * 100;
}
}
nodes
}
fn is_final(&self) -> bool {
self.goal_x == 0 && self.goal_y == 0
}
fn make_move(&self, x: i8, y: i8, dx: i8, dy: i8) -> Option<Grid> {
if x+dx < 0 || x+dx >= self.nodes.len() as i8 || y+dy < 0 || y+dy >= self.nodes[x as usize].len() as i8 {
return None;
}
if !self.nodes[x as usize][y as usize].is_viable_pair(&self.nodes[(x+dx) as usize][(y+dy) as usize]) {
return None;
}
let mut new_grid = self.clone();
new_grid.nodes[(x+dx) as usize][(y+dy) as usize].used += new_grid.nodes[x as usize][y as usize].used;
new_grid.nodes[(x+dx) as usize][(y+dy) as usize].recalculate_avail();
new_grid.nodes[x as usize][y as usize].used = 0;
new_grid.nodes[x as usize][y as usize].recalculate_avail();
if new_grid.goal_x == x && new_grid.goal_y == y {
new_grid.goal_x = x+dx;
new_grid.goal_y = y+dy;
}
Some(new_grid)
}
fn available_moves(&self) -> Vec<Grid> {
let mut moves = Vec::with_capacity(4);
for x in 0..self.nodes.len() as i8 {
for y in 0..self.nodes[x as usize].len() as i8 {
match self.make_move(x, y, -1, 0) {
Some(grid) => { moves.push(grid); },
None => {}
};
match self.make_move(x, y, 0, -1) {
Some(grid) => { moves.push(grid); },
None => {}
};
match self.make_move(x, y, 1, 0) {
Some(grid) => { moves.push(grid); },
None => {}
};
match self.make_move(x, y, 0, 1) {
Some(grid) => { moves.push(grid); },
None => {}
};
}
}
moves
}
}
fn main() {
let nodes = read_input();
let initial = Grid::new(nodes);
println!("Initial grid has {} possible moves", initial.available_moves().len());
let mut explored: HashSet<Grid> = HashSet::new();
let mut frontier: HashMap<Grid, u32> = HashMap::new();
frontier.insert(initial, 0);
let mut found_final = false;
while !found_final {
let (best_frontier, moves) = find_best_frontiers(&frontier);
let new_states = best_frontier.available_moves();
found_final = new_states.iter().any(|ref s| s.is_final());
for state in new_states {
if !(explored.contains(&state) || frontier.contains_key(&state)) {
frontier.insert(state, moves+1);
}
}
frontier.remove(&best_frontier);
explored.insert(best_frontier);
}
let (final_frontier, moves) = frontier.iter().find(|&(s, _)| s.is_final()).unwrap();
println!("It took {} moves to get the data", moves);
}
fn read_input() -> Vec<Node> {
let file = BufReader::new(File::open("input.txt").unwrap());
file.lines()
.skip(2)
.filter_map(|line| Node::from_str(line.unwrap().as_ref()).ok())
.collect()
}
fn find_best_frontiers(frontier: &HashMap<Grid, u32>) -> (Grid, u32) {
frontier.iter().min_by_key(|&(ref grid, &moves)| {
grid.goal_x as u32 + grid.goal_y as u32 + moves
}).map(|(&ref grid, &moves)| (grid.clone(), moves.clone())).unwrap()
}
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