added daily challenge

Author: Pasindu-Vishmika

1171. Remove Zero Sum Consecutive Nodes from Linked List.py

@@ -0,0 +1,27 @@
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, val=0, next=None):
+#         self.val = val
+#         self.next = next
+class Solution:
+    def removeZeroSumSublists(self, head: Optional[ListNode]) -> Optional[ListNode]:
+        dummy = ListNode(0)
+        dummy.next = head
+        prefixSumToNode = {}
+        prefixSum = 0
+        current = dummy
+        while current:
+            prefixSum += current.val
+            if prefixSum in prefixSumToNode:
+                prev = prefixSumToNode[prefixSum]
+                toRemove = prev.next
+                p = prefixSum + (toRemove.val if toRemove else 0)
+                while p != prefixSum:
+                    del prefixSumToNode[p]
+                    toRemove = toRemove.next
+                    p += toRemove.val if toRemove else 0
+                prev.next = current.next
+            else:
+                prefixSumToNode[prefixSum] = current
+            current = current.next
+        return dummy.next