fix:反转链表

02-链表/problem_solving_08.py

+"""
+反转链表
+"""
+from typing import Optional
+
+
+class ListNode:
+    def __init__(self, val=0, next=None):
+        self.val = val
+        self.next = next
+
+
+class Solution:
+    def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]:
+        """
+        反转链表:定义前节点和当前节点
+        :param head:
+        :return:
+        """
+        pre, curr = None, head
+        while curr is not None:
+            next = curr.next
+            curr.next = pre
+            pre = curr
+            curr = next
+        return pre
+
+
+if __name__ == '__main__':
+    # 1, 2, 6, 3, 4, 5, 6
+    l1 = ListNode(1)
+    l1.next = ListNode(2)
+    l1.next.next = ListNode(3)
+    l1.next.next.next = ListNode(4)
+    l1.next.next.next.next = ListNode(5)
+    # l1.next.next.next.next.next = ListNode(7)
+    # l1.next.next.next.next.next.next = ListNode(7)
+    # l2 = ListNode(5)
+    # l2.next = ListNode(6)
+    # l2.next.next = ListNode(1)
+    # l2.next.next.next = ListNode(8)
+    # l2.next.next.next.next = ListNode(4)
+    # l2.next.next.next.next.next = ListNode(5)
+    result = Solution().reverseList(l1)
+    while result:
+        print(result.val, end=' -> ')
+        result = result.next