.

packages/solver-r/src/snake.rs

@@ -11,7 +11,7 @@ pub fn move_snake(s: &mut Snake, dir: &Point) -> () {
     e.y = s[0].y + dir.y;
     s.insert(0, e);
 }
-pub fn will_self_collide(s: &Snake, dir: &Point) -> bool {
+pub fn snake_will_self_collide(s: &Snake, dir: &Point) -> bool {
     let next_head = Point {
         x: s[0].x + dir.x,
         y: s[0].y + dir.y,
@@ -19,7 +19,27 @@ pub fn will_self_collide(s: &Snake, dir: &Point) -> bool {
 
     (&s[0..(s.len() - 1)]).contains(&next_head)
 }
+pub fn get_snake_head(s: &Snake) -> Point {
+    s[0]
+}
+pub fn get_next_snake_head(s: &Snake, dir: &Point) -> Point {
+    Point {
+        x: s[0].x + dir.x,
+        y: s[0].y + dir.y,
+    }
+}
 
+#[test]
+fn it_should_return_head() {
+    let s = vec![
+        //
+        Point { x: 3, y: 0 },
+        Point { x: 2, y: 0 },
+        Point { x: 1, y: 0 },
+    ];
+
+    assert_eq!(get_snake_head(&s), Point { x: 3, y: 0 });
+}
 #[test]
 fn it_should_detect_self_collide() {
     let mut s = vec![
@@ -35,11 +55,22 @@ fn it_should_detect_self_collide() {
     move_snake(&mut s, &DIRECTION_UP);
     move_snake(&mut s, &DIRECTION_LEFT);
 
-    assert_eq!(will_self_collide(&s, &DIRECTION_DOWN), true);
+    assert_eq!(snake_will_self_collide(&s, &DIRECTION_DOWN), true);
 
     move_snake(&mut s, &DIRECTION_LEFT);
 
-    assert_eq!(will_self_collide(&s, &DIRECTION_DOWN), false);
+    assert_eq!(snake_will_self_collide(&s, &DIRECTION_DOWN), false);
+}
+#[test]
+fn it_should_detect_self_collide_2() {
+    let s = vec![
+        //
+        Point { x: 3, y: 0 },
+        Point { x: 2, y: 0 },
+        Point { x: 1, y: 0 },
+    ];
+
+    assert_eq!(snake_will_self_collide(&s, &DIRECTION_LEFT), true);
 }
 #[test]
 fn it_should_move_snake() {

packages/solver-r/src/snake_walk.rs

@@ -1,21 +1,58 @@
 use std::collections::HashSet;
 
 use crate::grid::{Cell, Grid, Point, DIRECTIONS};
-use crate::snake::Snake;
+use crate::snake::{
+    get_next_snake_head, get_snake_head, move_snake, snake_will_self_collide, Snake,
+};
 
 pub fn get_route_to_eat_all(
     grid: &Grid,
     walkable: Cell,
     initial_snake: &Snake,
     cells_to_eat: HashSet<Point>,
-) -> Vec<Snake> {
-    let mut targets = cells_to_eat.clone();
+) -> Vec<Point> {
+    // let mut targets: Vec<Point> = cells_to_eat.iter().map(|p| p.clone()).collect();
 
-    while let Some(p) = targets.iter().next().cloned() {
-        targets.remove(&p);
+    let mut targets: Vec<&Point> = cells_to_eat.iter().collect();
 
-        let mut open_list: HashSet<Snake> = HashSet::new();
+    let mut path: Vec<Point> = Vec::new();
+
+    let mut initial_snake = initial_snake.clone();
+
+    while let Some(target) = targets.pop() {
+        // prepare
+        let mut open_list: HashSet<(Snake, Vec<Point>)> = HashSet::new();
+        open_list.insert((initial_snake.clone(), Vec::new()));
+
+        while let Some(x) = open_list.iter().next().cloned() {
+            open_list.remove(&x);
+
+            let snake = x.0;
+            let mut sub_path = x.1;
+
+            if get_snake_head(&snake) == *target {
+                path.append(&mut sub_path);
+                initial_snake = snake;
+                break;
             }
-    for dir in DIRECTIONS {}
-    Vec::new()
+
+            for dir in DIRECTIONS {
+                if {
+                    let h = get_next_snake_head(&snake, &dir);
+                    grid.get_cell(&h) <= walkable
+                } && !snake_will_self_collide(&snake, &dir)
+                {
+                    let mut next_snake = snake.clone();
+                    move_snake(&mut next_snake, &dir);
+
+                    let mut next_sub_path = sub_path.clone();
+                    next_sub_path.push(dir.clone());
+
+                    open_list.insert((next_snake, next_sub_path));
+                }
+            }
+        }
+    }
+
+    path
 }