From 4bd8572fa512cc18568b1b339c18c675442aacb9 Mon Sep 17 00:00:00 2001
From: LeeTaek2T <137752192+LeeTaek2T@users.noreply.github.com>
Date: Sun, 17 Mar 2024 00:46:58 +0900
Subject: [PATCH] Update priority_queue.py

---
 priority_queue.py | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/priority_queue.py b/priority_queue.py
index 6aaf9e3..e335019 100644
--- a/priority_queue.py
+++ b/priority_queue.py
@@ -8,15 +8,17 @@ def push(self, item, priority):
     self._sift_up(len(self.heap) - 1)
 
   def pop(self):
-    if len(self.heap) > 1:
-      entry = self.heap.pop()
-      self._sift_down(0)
-      return entry[1]
-    elif len(self.heap) == 1:
-      entry = self.heap.pop()
-      return entry[1]
+    if self.heap:
+      if len(self.heap) > 1:
+        top_element = self.heap[0]
+        self.heap[0] = self.heap.pop()
+        self._sift_down(0)
+        return top_element[1]
+      else:
+        return self.heap.pop()[1]
     else:
       return None
+  
   def _sift_up(self, index):
     while index > 0:
       parent_index = (index - 1) // 2