From e39f23b24e4c452134d16699ba84eff14cac0a88 Mon Sep 17 00:00:00 2001
From: Nervonment <nervonment@outlook.com>
Date: Fri, 14 Jun 2024 14:33:53 +0800
Subject: [PATCH] fix bug

---
 src/techniques/naked_subsets.rs | 45 ++++++++++++++++++---------------
 1 file changed, 24 insertions(+), 21 deletions(-)

diff --git a/src/techniques/naked_subsets.rs b/src/techniques/naked_subsets.rs
index 39ad041..bdc71cf 100644
--- a/src/techniques/naked_subsets.rs
+++ b/src/techniques/naked_subsets.rs
@@ -376,29 +376,32 @@ where
                         removes,
                     }
                 });
-            if self.0.is_none() {
-                self.0 =
-                    naked_subset(k, state, |r, c| (r, c)).map(|(house, cells, nums, removes)| {
-                        NakedSubsetInfo {
-                            k,
-                            house: House::Row(house),
-                            cells,
-                            nums,
-                            removes,
-                        }
-                    });
-                if self.0.is_none() {
-                    self.0 = naked_subset(k, state, |r, c| (c, r)).map(
-                        |(house, cells, nums, removes)| NakedSubsetInfo {
-                            k,
-                            house: House::Column(house),
-                            cells,
-                            nums,
-                            removes,
-                        },
-                    );
+            if self.0.is_some() {
+                return;
+            }
+
+            self.0 = naked_subset(k, state, |r, c| (r, c)).map(|(house, cells, nums, removes)| {
+                NakedSubsetInfo {
+                    k,
+                    house: House::Row(house),
+                    cells,
+                    nums,
+                    removes,
                 }
+            });
+            if self.0.is_some() {
+                return;
             }
+
+            self.0 = naked_subset(k, state, |r, c| (c, r)).map(|(house, cells, nums, removes)| {
+                NakedSubsetInfo {
+                    k,
+                    house: House::Column(house),
+                    cells,
+                    nums,
+                    removes,
+                }
+            });
         }
     }
     fn appliable(&self) -> bool {