From c467fe5ba42545827d769c360aa404767308ac18 Mon Sep 17 00:00:00 2001
From: AliceRoselia <63040919+AliceRoselia@users.noreply.github.com>
Date: Sun, 14 Dec 2025 14:14:27 +0700
Subject: [PATCH] Simplify futility pruning

Passed non regression STC:
https://tests.stockfishchess.org/tests/view/693e642c46f342e1ec20f68d
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 107968 W: 28080 L: 27937 D: 51951
Ptnml(0-2): 381, 12708, 27626, 12925, 344

Passed non regression LTC:
https://tests.stockfishchess.org/tests/view/693ff10c46f342e1ec20fa6a
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 334266 W: 85271 L: 85370 D: 163625
Ptnml(0-2): 179, 36395, 94086, 36292, 181

closes https://github.com/official-stockfish/Stockfish/pull/6484

Bench: 2987379
---
 src/search.cpp | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/search.cpp b/src/search.cpp
index 64f85bcbe..adb7985d2 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -868,9 +868,8 @@ Value Search::Worker::search(
         auto futility_margin = [&](Depth d) {
             Value futilityMult = 76 - 23 * !ss->ttHit;
 
-            return futilityMult * d                               //
-                 - 2474 * improving * futilityMult / 1024         //
-                 - 331 * opponentWorsening * futilityMult / 1024  //
+            return futilityMult * d
+                 - (2474 * improving + 331 * opponentWorsening) * futilityMult / 1024  //
                  + std::abs(correctionValue) / 174665;
         };