Merge pull request #2630 from TheHong/py-1721

Create 1721-swapping-nodes-in-a-linked-list.py

Author: MHamiid

python/1721-swapping-nodes-in-a-linked-list.py

@@ -0,0 +1,20 @@
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, val=0, next=None):
+#         self.val = val
+#         self.next = next
+class Solution:
+    def swapNodes(self, head: Optional[ListNode], k: int) -> Optional[ListNode]:
+        right_pointer = head
+        for _ in range(1, k):
+            right_pointer = right_pointer.next
+        left_kth_node = right_pointer
+
+        left_pointer = head
+        while right_pointer is not None:
+            right_kth_node = left_pointer
+            right_pointer = right_pointer.next
+            left_pointer = left_pointer.next
+
+        left_kth_node.val, right_kth_node.val = right_kth_node.val, left_kth_node.val
+        return head