From fc5872a5af00249dc6381648a4c3db9960d85319 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jana=20D=C3=B6nszelmann?= <jana@donsz.nl>
Date: Fri, 2 Jan 2026 15:03:54 +0100
Subject: [PATCH] don't allow moving towers of the same color to empty spots

---
 src/main.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/main.rs b/src/main.rs
index 73931af..6f7dae2 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -280,6 +280,13 @@ impl<const TOWER_HEIGHT: usize> Game<TOWER_HEIGHT> {
                     continue;
                 }
 
+                let rings = self.towers[from_tower].rings;
+                if rings[1..].iter().all(|i| i == &rings[0])
+                    && self.towers[to_tower].rings[0].is_none()
+                {
+                    continue;
+                }
+
                 let m = Move::new(from_tower, to_tower);
                 if self.try_make_move(m, true).is_ok() {
                     res.push(m);