From 27e675aec44cd620f6cbf8cc372b4efc49216cf1 Mon Sep 17 00:00:00 2001
From: En-En <39373446+En-En-Code@users.noreply.github.com>
Date: Mon, 30 Jan 2023 16:36:39 -0500
Subject: [PATCH] Added key check before TT write.

---
 src/search.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/search.c b/src/search.c
index 1a79d2e..870fceb 100644
--- a/src/search.c
+++ b/src/search.c
@@ -280,6 +280,11 @@ int pvSearch(Board *board, int depth, int alpha, int beta, const int nullmove) {
 		flag = LOWER_BOUND;
 
 	// Always replace the entry for the TT
+	// UNLESS the position currently in there has a different key and goes deeper
+	if (tt[index].key != board->key && tt[index].depth > depth) {
+		return bestScore;
+	}
+
 	tt[index] = compressEntry(board->key, &bestMove, bestScore, depth, flag);
 
 	return bestScore;