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

Author: kamyu104

Python/swapping-nodes-in-a-linked-list.py

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+# Time:  O(n)
+# Space: O(1)
+
+# Definition for singly-linked list.
+class ListNode(object):
+    def __init__(self, val=0, next=None):
+        pass
+
+
+class Solution(object):
+    def swapNodes(self, head, k):
+        """
+        :type head: ListNode
+        :type k: int
+        :rtype: ListNode
+        """
+        left, right, curr = None, None, head
+        while curr:
+            k -= 1
+            if right:
+                right = right.next
+            if k == 0:
+                left = curr
+                right = head
+            curr = curr.next
+        left.val, right.val = right.val, left.val
+        return head