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map-sum-pairs.py
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map-sum-pairs.py
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# https://leetcode.com/problems/map-sum-pairs/
from collections import defaultdict
class Node:
def __init__(self, key: str, value: int):
self.key = key
self.value = value
self.next = None
self.prev = None
class LinkedList:
def __init__(self):
self.head = None
self.tail = None
def sum(self, prefix: str) -> int:
result = 0
node = self.head
while node:
if node.key.startswith(prefix):
result += node.value
node = node.next
return result
def add(self, node: Node):
if self.head is None:
self.head = self.tail = node
else:
self.tail.next = node
node.prev = self.tail
self.tail = self.tail.next
def remove(self, node: Node):
if node is self.head:
self.head = self.head.next
if self.head is None:
self.tail = None
else:
self.head.prev = None
elif node is self.tail:
n = self.tail
self.tail.prev.next = None
self.tail = self.tail.prev
n.prev = None
else:
node.prev.next = node.next
node.next.prev = node.prev
node.next = node.prev = None
class MapSum:
def __init__(self):
self.storage = defaultdict(LinkedList)
self.nodes = {}
def insert(self, key: str, val: int) -> None:
if key in self.nodes:
self.storage[key[0]].remove(self.nodes[key])
node = Node(key, val)
self.storage[key[0]].add(node)
self.nodes[key] = node
def sum(self, prefix: str) -> int:
return self.storage[prefix[0]].sum(prefix)