feat: Adds find_path_one_to_many for directed graphs

src/directed/mod.rs

@@ -15,7 +15,28 @@ use crate::{
     },
 };
 use fxhash::FxHashSet;
-use std::{collections::VecDeque, ops::Not, rc::Rc};
+use std::{
+    collections::{HashMap, VecDeque},
+    ops::Not,
+    path,
+    rc::Rc,
+};
+
+// Helper function for constructing the path
+fn construct_path(parents: &[(Sym, Sym)], start_id: Sym, goal_id: Sym, path: &mut Vec<Sym>) {
+    let mut current_id = goal_id;
+    path.push(current_id);
+    while current_id != start_id {
+        if let Some(parent_pair) = parents.iter().find(|(node, _)| *node == current_id) {
+            current_id = parent_pair.1;
+            path.push(current_id);
+        } else {
+            break; // This should not happen if the path exists
+        }
+    }
+
+    path.reverse(); // Reverse to get the path from start to goal
+}
 
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct DirectedGraph {
@@ -184,32 +205,81 @@ impl DirectedGraph {
             .collect()
     }
 
-    pub fn find_path(
+    pub fn find_path_one_to_many<'a>(
         &self,
-        from: impl AsRef<str>,
-        to: impl AsRef<str>,
-    ) -> GraphInteractionResult<NodeVec> {
-        // Helper function for constructing the path
-        fn construct_path(
-            parents: &[(Sym, Sym)],
-            start_id: Sym,
-            goal_id: Sym,
-            path: &mut Vec<Sym>,
-        ) {
-            let mut current_id = goal_id;
-            path.push(current_id);
-            while current_id != start_id {
-                if let Some(parent_pair) = parents.iter().find(|(node, _)| *node == current_id) {
-                    current_id = parent_pair.1;
-                    path.push(current_id);
-                } else {
-                    break; // This should not happen if the path exists
-                }
+        from: impl AsRef<str> + 'a,
+        to: impl IntoIterator<Item = impl AsRef<str> + 'a>,
+    ) -> GraphInteractionResult<Vec<NodeVec>> {
+        let mut paths = Vec::<Vec<Sym>>::new();
+        let mut path_cache = HashMap::<(Sym, Sym), Vec<Sym>>::new();
+        let from = self.get_internal(from)?;
+
+        let queue = unsafe { self.u32x1_queue_0() };
+        let visited = unsafe { self.u32x1_set_0() };
+        let path_buf = unsafe { self.u32x1_vec_0() };
+        let path_buf2 = unsafe { self.u32x1_vec_1() };
+        let path = unsafe { self.u32x2_vec_0() }; // To track the path back to the start node
+
+        'to: for to in to {
+            path_buf.clear();
+            path_buf2.clear();
+
+            let to = self.get_internal(to)?;
+
+            if from == to {
+                path_cache.insert((from, to), vec![from]);
+                paths.push(vec![from]);
+                continue 'to;
             }
 
-            path.reverse(); // Reverse to get the path from start to goal
+            queue.clear();
+            visited.clear();
+
+            // Initialize
+            queue.push_back(to);
+            visited.insert(to);
+
+            while let Some(current) = queue.pop_front() {
+                if let Some(pre_calculated_path) = path_cache.get(&(from, current)) {
+                    construct_path(path, current, to, path_buf);
+                    pre_calculated_path.iter().for_each(|&s| path_buf2.push(s));
+                    for node in path_buf.drain(..).skip(1) {
+                        path_buf2.push(node);
+                    }
+                    path_cache.insert((from, to), path_buf2.clone());
+                    paths.push(path_buf2.clone());
+                    continue 'to;
+                }
+                if let LazySet::Initialized(parents) = self.parent_map.get(current) {
+                    for &parent in parents.iter() {
+                        if visited.insert(parent) {
+                            path.push((current, parent));
+                            if parent == from {
+                                // Construct the path and place it in `path_buf`
+                                construct_path(path, from, to, path_buf);
+                                path_cache.insert((from, to), path_buf.clone());
+                                paths.push(path_buf.clone());
+                                continue 'to;
+                            }
+                            queue.push_back(parent);
+                        }
+                    }
+                }
+            }
+            paths.push(vec![]);
         }
 
+        Ok(paths
+            .into_iter()
+            .map(|path| self.resolve_mul_slice(&path))
+            .collect())
+    }
+
+    pub fn find_path(
+        &self,
+        from: impl AsRef<str>,
+        to: impl AsRef<str>,
+    ) -> GraphInteractionResult<NodeVec> {
         let from = self.get_internal(from)?;
         let to = self.get_internal(to)?;
 
@@ -628,6 +698,39 @@ mod tests {
         assert_eq!(dg.children(["A"]).unwrap(), ["H", "B"]);
     }
 
+    #[test]
+    fn dg_find_path_one_to_many() {
+        let mut builder = DirectedGraphBuilder::new();
+        // We put more than 8 children to
+        // test if SIMD actually workd
+        builder.add_path(["A", "B", "C", "D"]);
+        let dg = builder.clone().build_directed();
+        assert_eq!(
+            dg.find_path_one_to_many("A", vec!["A", "B", "C", "D"])
+                .unwrap(),
+            [
+                vec!["A"],
+                vec!["A", "B"],
+                vec!["A", "B", "C"],
+                vec!["A", "B", "C", "D"],
+            ]
+        );
+
+        builder.add_path(["A", "H", "D"]);
+        let dg = builder.clone().build_directed();
+        assert_eq!(
+            dg.find_path_one_to_many("A", vec!["A", "B", "C", "D"])
+                .unwrap(),
+            [
+                vec!["A"],
+                vec!["A", "B"],
+                vec!["A", "B", "C"],
+                vec!["A", "H", "D"],
+            ]
+        );
+        assert_eq!(dg.children(["A"]).unwrap(), ["H", "B"]);
+    }
+
     #[test]
     fn dg_find_least_common_parents() {
         let mut builder = DirectedGraphBuilder::new();