706.md

Design HashMap

Description

link

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Solution

• See Code

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Code

Complexity T : O(1) M : O(n)

class MyHashMap:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.buckets = 1000
        self.itemsperbucket = 1001
        self.table = [[] for _ in range(self.buckets)]

    def hash(self, key):
        return key % self.buckets

    def pos(self, key):
        return key // self.itemsperbucket

    def put(self, key: int, value: int) -> None:
        """
        value will always be non-negative.
        """
        bucket_num = self.hash(key)
        if not self.table[bucket_num]:
            self.table[bucket_num] = [-1 for _ in range(self.itemsperbucket)]
        bucket_pos = self.pos(key)
        self.table[bucket_num][bucket_pos] = 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
        """
        bucket_num = self.hash(key)
        bucket_pos = self.pos(key)
        if not self.table[bucket_num]:
            return -1
        return self.table[bucket_num][bucket_pos]

    def remove(self, key: int) -> None:
        """
        Removes the mapping of the specified value key if this map contains a mapping for the key
        """
        bucket_num = self.hash(key)
        bucket_pos = self.pos(key)
        if self.table[bucket_num]:
            self.table[bucket_num][bucket_pos] = -1