Bug fixes and improvements (#1298)

* Fix is_empty() implementation in the stack and queue chapter

* Update en/CONTRIBUTING.md

* Remove "剩余" from the state definition of knapsack problem

* Sync zh and zh-hant versions

* Update the stylesheets of code tabs

* Fix quick_sort.rb

* Fix TS code

* Update chapter_paperbook

* Upload the manuscript of 0.1 section

* Fix binary_tree_dfs.rb

* Bug fixes

* Update README

* Update README

* Update README

* Update README.md

* Update README

* Sync zh and zh-hant versions

* Bug fixes

codes/python/chapter_stack_and_queue/array_stack.py

@@ -18,7 +18,7 @@ class ArrayStack:
 
     def is_empty(self) -> bool:
         """判断栈是否为空"""
-        return self._stack == []
+        return self.size() == 0
 
     def push(self, item: int):
         """入栈"""

codes/python/chapter_stack_and_queue/linkedlist_deque.py

@@ -30,7 +30,7 @@ class LinkedListDeque:
 
     def is_empty(self) -> bool:
         """判断双向队列是否为空"""
-        return self.size() == 0
+        return self._size == 0
 
     def push(self, num: int, is_front: bool):
         """入队操作"""

codes/python/chapter_stack_and_queue/linkedlist_queue.py

@@ -26,7 +26,7 @@ class LinkedListQueue:
 
     def is_empty(self) -> bool:
         """判断队列是否为空"""
-        return not self._front
+        return self._size == 0
 
     def push(self, num: int):
         """入队"""

codes/python/chapter_stack_and_queue/linkedlist_stack.py

@@ -25,7 +25,7 @@ class LinkedListStack:
 
     def is_empty(self) -> bool:
         """判断栈是否为空"""
-        return not self._peek
+        return self._size == 0
 
     def push(self, val: int):
         """入栈"""