706. Design HashMap

Posted 2021-01-15 bernieloveslife

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.

Example:

MyHashMap hashMap = new MyHashMap();
hashMap.put(1, 1);
hashMap.put(2, 2);
hashMap.get(1); // returns 1
hashMap.get(3); // returns -1 (not found)
hashMap.put(2, 1); // update the existing value
hashMap.get(2); // returns 1
hashMap.remove(2); // remove the mapping for 2
hashMap.get(2); // returns -1 (not found)

Note:

• All keys and values will be in the range of [0, 1000000].
• The number of operations will be in the range of [1, 10000].
• Please do not use the built-in HashMap library.

class MyHashMap:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.a = []
        self.b = []


    def put(self, key, value):
        """
        value will always be non-negative.
        :type key: int
        :type value: int
        :rtype: void
        """
        if key in self.a:
            pos = self.a.index(key)
            self.b[pos] = value
        else:
            self.a.append(key)
            self.b.append(value)
        return

    def get(self, key):
        """
        Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key
        :type key: int
        :rtype: int
        """
        if key in self.a:
            pos = self.a.index(key)
            return self.b[pos]
        else:
            return -1

    def remove(self, key):
        """
        Removes the mapping of the specified value key if this map contains a mapping for the key
        :type key: int
        :rtype: void
        """
        if key in self.a:
            pos = self.a.index(key)
            self.a.pop(pos)
            self.b.pop(pos)
        return 
# Your MyHashMap object will be instantiated and called as such:
# obj = MyHashMap()
# obj.put(key,value)
# param_2 = obj.get(key)
# obj.remove(key)