LeetCode 706 Design HashMap 解题报告
题目要求
Design a HashMap without using any built-in hash table libraries.
To be specific, your design should include these functions:
put(key, value): Insert a (key, value) pair into the HashMap. If the value already exists in the HashMap, update the value.get(key): Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key.remove(key): Remove the mapping for the value key if this map contains the mapping for the key.
题目分析及思路
要求不使用任何内置的hash table库设计一个HashMap。具体要求是：1）put函数能将一对(key, value)插入到HashMap，若已经有value，则进行更新；2）get函数能获得对应key的value，若不存在key，则返回-1；3）remove函数能在key存在的时候去除key以及key对应的value。可以将key和value分别设置为列表，put函数里对key的存在性先进行判断，然后确定添加还是更新。get和remove函数同样需要对key的存在性先进行判断，然后前者获取对应key的索引，后者将key和与key同位置的value一起去掉。
python代码
class MyHashMap:
def __init__(self):
"""
Initialize your data structure here.
"""
self.keys = []
self.vals = []
def put(self, key: int, value: int) -> None:
"""
value will always be non-negative.
"""
if key not in self.keys:
self.keys.append(key)
self.vals.append(value)
else:
self.vals[self.keys.index(key)] = value
def get(self, key: int) -> int:
"""
Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key
"""
if key in self.keys:
return self.vals[self.keys.index(key)]
else:
return -1
def remove(self, key: int) -> None:
"""
Removes the mapping of the specified value key if this map contains a mapping for the key
"""
if key in self.keys:
idx = self.keys.index(key)
self.keys.remove(key)
self.vals.pop(idx)
# Your MyHashMap object will be instantiated and called as such:
# obj = MyHashMap()
# obj.put(key,value)
# param_2 = obj.get(key)
# obj.remove(key)
