logic fixes and nits

src/complexagent.rs

@@ -142,11 +142,8 @@ impl FutureMoves {
 
     fn compute_values(&mut self) {
         for depth in (0..=self.current_depth).rev() {
-            let nodes_at_depth: Vec<usize> = self
-                .arena
-                .iter()
-                .enumerate()
-                .filter_map(|(idx, node)| (self.depth_of(node.parent) == depth).then_some(idx))
+            let nodes_at_depth: Vec<usize> = (0..self.arena.len())
+                .filter(|&idx| self.depth_of(idx) == depth)
                 .collect();
 
             for idx in nodes_at_depth {
@@ -166,9 +163,10 @@ impl FutureMoves {
         }
     }
 
-    fn depth_of(&self, node_parent: Option<usize>) -> usize {
+    /// Given an index from `self.arena`, what depth is it at? 0-indexed
+    fn depth_of(&self, node_parent: usize) -> usize {
         let mut depth = 0;
-        let mut current = node_parent;
+        let mut current = Some(node_parent);
         while let Some(parent_idx) = current {
             depth += 1;
             current = self.arena[parent_idx].parent;
@@ -203,7 +201,7 @@ impl FutureMoves {
             })
             .inspect(|&root| {
                 self.current_root = Some(root);
-                self.current_depth = self.max_depth - self.depth_of(Some(root));
+                self.current_depth = self.max_depth - self.depth_of(root);
                 self.prune_unrelated();
             })
             .is_some()
@@ -254,8 +252,8 @@ pub struct ComplexAgent {
 }
 
 impl ComplexAgent {
-    pub fn new(color: Piece) -> Self {
-        const MAX_DEPTH: usize = 6;
+    pub const fn new(color: Piece) -> Self {
+        const MAX_DEPTH: usize = 8;
         Self {
             color,
             future_moves: FutureMoves::new(color, MAX_DEPTH),