From 0adb59dc7fdfe40aa8c813bbe08b6a3a9ac436e1 Mon Sep 17 00:00:00 2001
From: Simon Gardling <titaniumtown@proton.me>
Date: Tue, 25 Feb 2025 11:23:14 -0500
Subject: [PATCH] initial rewrite of lazy_children logic

---
 src/complexagent.rs       |  4 ++--
 src/logic/future_moves.rs | 37 ++++++++++++-------------------------
 src/logic/move.rs         |  7 +++++++
 3 files changed, 21 insertions(+), 27 deletions(-)

diff --git a/src/complexagent.rs b/src/complexagent.rs
index ca680a8..dc3d4b4 100644
--- a/src/complexagent.rs
+++ b/src/complexagent.rs
@@ -12,8 +12,8 @@ pub struct ComplexAgent {
 #[allow(dead_code)]
 impl ComplexAgent {
     pub const fn new(color: Piece) -> Self {
-        const MAX_DEPTH: usize = 9;
-        const NON_LAZY_DEPTH: usize = 9;
+        const MAX_DEPTH: usize = 18;
+        const NON_LAZY_DEPTH: usize = 5;
         Self {
             color,
             future_moves: FutureMoves::new(color, MAX_DEPTH, NON_LAZY_DEPTH),
diff --git a/src/logic/future_moves.rs b/src/logic/future_moves.rs
index e548b6a..1fdcbda 100644
--- a/src/logic/future_moves.rs
+++ b/src/logic/future_moves.rs
@@ -113,7 +113,7 @@ impl FutureMoves {
 
         // use [`Board::all_positions`] here instead of [`Board::possible_moves`]
         // because we use [`Board::what_if`] later and we want to reduce calls to [`Board::propegate_from_dry`]
-        let mut new: Vec<Move> = Board::all_positions()
+        let new: Vec<Move> = Board::all_positions()
             .flat_map(|(i, j)| {
                 parent
                     .board
@@ -133,37 +133,24 @@ impl FutureMoves {
             })
             .collect();
 
-        // negative, because we want the max value to be at the first index
-        // abs because we want the most EXTREME possible outcome (win or lose for example)
-        new.sort_by_key(|x| -x.self_value.abs());
-
         // keep the TOP_K children of their magnitude
-        const TOP_K_CHILDREN: usize = 2;
-
-        // we want to keep only the greatest magnitude moves
-        if lazy_children && new.len() > TOP_K_CHILDREN {
-            new.drain(TOP_K_CHILDREN..);
-        }
+        const TOP_K_CHILDREN: usize = 10;
 
         let start_idx = self.arena.len();
-        if parent.lazy_children && !lazy_children {
-            self.arena[parent_idx].lazy_children = false;
-            // this move's children are being regenerated after lazy child expiration, don't append first node
-            if new.len() > TOP_K_CHILDREN {
-                self.arena.extend(new.drain(TOP_K_CHILDREN..));
-            } else {
-                // nothing will be appended
-                // even though it was sorted the first time around
-                // there's still no more than one element (which is already in the arena)
-                return None;
-            }
-        } else {
-            self.arena.extend(new);
-        }
+        self.arena.extend(new);
 
         let new_indices = start_idx..self.arena.len();
 
         self.arena[parent_idx].children.extend(new_indices.clone());
+        let mut parent_copy = self.arena[parent_idx].clone();
+        parent_copy.sort_children(self.arena.as_mut_slice());
+        self.arena[parent_idx] = parent_copy;
+
+        if lazy_children && new_indices.clone().count() > TOP_K_CHILDREN {
+            for i in new_indices.clone().skip(TOP_K_CHILDREN) {
+                self.arena[i].lazy_children = true;
+            }
+        }
 
         Some(new_indices)
     }
diff --git a/src/logic/move.rs b/src/logic/move.rs
index c532f04..9e8979d 100644
--- a/src/logic/move.rs
+++ b/src/logic/move.rs
@@ -86,4 +86,11 @@ impl Move {
 
         BVM.board_value(&self.board, agent_color)
     }
+
+    /// Sort children of the [`Move`] by their self_value in `arena`
+    pub fn sort_children(&mut self, arena: &[Move]) {
+        // negative, because we want the max value to be at the first index
+        // abs because we want the most EXTREME possible outcome (win or lose for example)
+        self.children.sort_by_key(|&i| -arena[i].self_value.abs());
+    }
 }