Merge pull request wangzheng0822#162 from Danielyan86/master

[Python]增加链表部分for遍历方法，调整代码格式

python/06_linkedlist/singly_linked_list.py

@@ -6,23 +6,23 @@
 """
 from typing import Optional
 
+
 class Node:
-    
-    def __init__(self, data: int, next=None):
+
+    def __init__(self, data: int, next_node=None):
         self.data = data
-        self._next = next
-    
+        self._next = next_node
+
 
 class SinglyLinkedList:
 
     def __init__(self):
         self._head = None
-    
+
     def find_by_value(self, value: int) -> Optional[Node]:
         p = self._head
         while p and p.data != value:
             p = p._next
-
         return p
 
     def find_by_index(self, index: int) -> Optional[Node]:
@@ -31,22 +31,21 @@ def find_by_index(self, index: int) -> Optional[Node]:
         while p and position != index:
             p = p._next
             position += 1
-
         return p
 
     def insert_value_to_head(self, value: int):
         new_node = Node(value)
         self.insert_node_to_head(new_node)
-    
+
     def insert_node_to_head(self, new_node: Node):
         if new_node:
             new_node._next = self._head
             self._head = new_node
-    
+
     def insert_value_after(self, node: Node, value: int):
         new_node = Node(value)
         self.insert_node_after(node, new_node)
-    
+
     def insert_node_after(self, node: Node, new_node: Node):
         if not node or not new_node:
             return
@@ -66,7 +65,7 @@ def insert_node_before(self, node: Node, new_node: Node):
         current = self._head
         while current._next and current._next != node:
             current = current._next
-        if not current._next:   # node is not even in the list
+        if not current._next:  # node is not even in the list
             return
         new_node._next = node
         current._next = new_node
@@ -83,13 +82,13 @@ def delete_by_node(self, node: Node):
         while current and current._next != node:
             current = current._next
         if not current:  # node not in the list
-            return 
+            return
         current._next = None
 
     def delete_by_value(self, value: int):
         if not self._head or not value:
             return
-        fake_head = Node(value+1)
+        fake_head = Node(value + 1)
         fake_head._next = self._head
         prev, current = fake_head, self._head
         while current:
@@ -100,7 +99,7 @@ def delete_by_value(self, value: int):
         if prev._next:
             prev._next = None
         self._head = fake_head._next  # in case head.data == value
-    
+
     def __repr__(self) -> str:
         nums = []
         current = self._head
@@ -112,6 +111,13 @@ def __repr__(self) -> str:
         else:
             return ""
 
+    # 重写__iter__方法，方便for关键字调用打印值
+    def __iter__(self):
+        node = self._head
+        while node:
+            yield node.data
+            node = node._next
+
     def print_all(self):
         current = self._head
         if current:
@@ -136,4 +142,6 @@ def print_all(self):
     l.delete_by_node(node11)
     l.delete_by_node(l._head)
     l.delete_by_value(13)
-    print(l)
+    print(l)
+    for value in l:
+        print(value)