feat(528-swapping-nodes-in-a-ll): add py3 solution

0528_swapping-nodes-in-a-linked-list/python3/using_dict.py

@@ -0,0 +1,17 @@
+# NOTE: Not the best approach, since we use O(N) space
+# Time: O(N)
+class Solution:
+    def swapNodes(self, head: Optional[ListNode], k: int) -> Optional[ListNode]:
+        # Figure out length of LL and cache nodes by the index
+        length = 0
+        cache = {}
+        
+        ptr = head
+        while ptr != None:
+            cache[length] = ptr
+            length += 1
+            ptr = ptr.next
+        
+        cache[k - 1].val, cache[length - k].val = cache[length - k].val, cache[k - 1].val
+        
+        return head