reverse linked list solution

Author: jungsiroo

reverse-linked-list/jungsiroo.py

@@ -0,0 +1,29 @@
+class Solution:
+    def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]:
+        # iterative way
+
+        """
+        prev, curr = None, head
+        while curr:
+            tmp_nxt = curr.next
+            
+            curr.next = prev
+            prev, curr = curr, tmp_nxt
+
+        return prev
+        """
+
+        # Recursive Way
+        if head is None or head.next is None:
+            return head
+
+        new_head = self.reverseList(head.next)
+        head.next.next = head # reversing pointer
+        head.next = None
+        return new_head
+
+        # 둘 다 시간복잡도 O(n)
+        # 하지만 재귀의 경우 콜스택에 따른 공간복잡도 O(n)을 소요
+        # iterative 방식은 O(1)
+                
+