add more code for 81 (WIP)

src/euler81/src/main.rs

@@ -1,108 +1,82 @@
+use std::cell::RefCell;
+use std::collections::HashSet;
 use std::fs;
+use std::iter::Cycle;
 use std::path::Path;
+use std::rc::Rc;
 
 const LENGTH: usize = 80;
 
-struct Matrix {
-    data: Vec<Vec<u32>>,
-}
+type Coordinate = (usize, usize);
 
-#[derive(Clone, Eq, PartialEq, Hash)]
-enum Direction {
-    Down,
-    Right,
+struct Matrix {
+    data: Vec<Vec<Node>>,
 }
 
 impl Matrix {
     fn load(f: &Path) -> Self {
-        let data: Vec<Vec<u32>> = fs::read_to_string(f)
+        let mut data: Vec<Vec<_>> = fs::read_to_string(f)
             .unwrap()
             .split_whitespace()
             .map(|line| {
                 line.split(',')
                     .into_iter()
                     .map(|number| number.parse::<u32>().unwrap())
+                    .map(Node::from)
                     .collect()
             })
             .collect();
+        data[0][0].is_infinity = false;
         assert_eq!(data.len(), LENGTH);
         assert!(data.iter().all(|subvec| subvec.len() == LENGTH));
         Self { data }
     }
-
-    fn calculate_sum_along_route(&self, route: &[Direction]) -> u32 {
-        assert_eq!(route.len() / 2, LENGTH - 1);
-        let mut i = 0;
-        let mut j = 0;
-        let mut sum = self.data[i][j];
-        for step in route {
-            match step {
-                Direction::Down => {
-                    i += 1;
-                }
-                Direction::Right => {
-                    j += 1;
-                }
-            }
-            sum += self.data[i][j];
-        }
-        sum
-    }
 }
 
 fn main() {
     let matrix = Matrix::load(Path::new("p081_matrix.txt"));
-    let permutations = calculate_permutations(LENGTH - 1);
-    assert_eq!(permutations.len(), (LENGTH - 1).pow(2));
-    let mut sums = vec![];
-
-    for route in permutations.into_iter() {
-        let sum = matrix.calculate_sum_along_route(&route);
-        sums.push(sum);
-    }
-    sums.sort_unstable();
-    println!("{}", sums.last().unwrap());
+    let dijkstra = Dijkstra::new(matrix);
 }
 
-fn calculate_permutations(length: usize) -> Vec<Vec<Direction>> {
-    let mut base = vec![Direction::Down; length];
-    base.append(&mut vec![Direction::Right; length]);
-    generate2(length, base)
+struct Dijkstra {
+    initial: Coordinate,
+    matrix: Matrix,
+    unvisited: Vec<Coordinate>,
 }
 
-/// https://en.wikipedia.org/wiki/Heap%27s_algorithm
-/// produces OOM, or is otherwise too slow
-fn generate(length: usize, mut vec: Vec<Direction>) -> Vec<Vec<Direction>> {
-    let mut result = vec![vec.clone()];
-    let mut c = vec![0; length];
-
-    let mut i = 1;
-    while i < length {
-        if c[i] < i {
-            if i % 2 == 0 {
-                vec.swap(0, i);
-            } else {
-                vec.swap(c[i], i)
+impl Dijkstra {
+    fn new(matrix: Matrix) -> Self {
+        let initial = (0, 0);
+        let unvisited: Vec<_> = (0..LENGTH)
+            .flat_map(|x| (0..LENGTH).zip([x].into_iter().cycle()))
+            .filter(|value| *value != (0, 0))
+            .collect();
+        assert_eq!(unvisited.len(), LENGTH * LENGTH - 1);
+        Self {
+            initial,
+            matrix,
+            unvisited,
         }
-            result.push(vec.clone());
-
-            c[i] += 1;
-            i = 1;
-        } else {
-            c[i] = 0;
-            i += 1;
     }
 }
 
-    result
+#[derive(PartialEq, Eq, Hash)]
+struct Node {
+    is_infinity: bool,
+    value: u32,
 }
 
-fn generate2(length: usize, mut vec: Vec<Direction>) -> Vec<Vec<Direction>> {
-    let orig = vec.clone();
-    let mut result = vec![vec.clone()];
-    for i in 1..=length {
-        // vec.remove
-        todo!()
+impl From<u32> for Node {
+    fn from(value: u32) -> Self {
+        Node {
+            is_infinity: true,
+            value,
+        }
+    }
+}
+
+impl From<Node> for Rc<RefCell<Node>> {
+    fn from(node: Node) -> Self {
+        Rc::new(RefCell::new(node))
     }
-    result
 }