Package g0701_0800.s0706_design_hashmap

Class MyHashMap

  • All Implemented Interfaces:
    
public final class MyHashMap

    706 - Design HashMap\.

    Easy

    Design a HashMap without using any built-in hash table libraries.

    Implement the MyHashMap class:

    • MyHashMap() initializes the object with an empty map.

    • void put(int key, int value) inserts a (key, value) pair into the HashMap. If the key already exists in the map, update the corresponding value.

    • int get(int key) returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key.

    • void remove(key) removes the key and its corresponding value if the map contains the mapping for the key.

    Example 1:

    Input

    "MyHashMap", "put", "put", "get", "get", "put", "get", "remove", "get"

    [ [], 1, 1, 2, 2, 1, 3, 2, 1, 2, 2, 2]

    Output: null, null, null, 1, -1, null, 1, null, -1

    Explanation:

    MyHashMap myHashMap = new MyHashMap();
myHashMap.put(1, 1); // The map is now [[1,1]]
myHashMap.put(2, 2); // The map is now [[1,1], [2,2]]
myHashMap.get(1); // return 1, The map is now [[1,1], [2,2]]
myHashMap.get(3); // return -1 (i.e., not found), The map is now [[1,1], [2,2]]
myHashMap.put(2, 1); // The map is now [[1,1], [2,1]] (i.e., update the existing value)
myHashMap.get(2); // return 1, The map is now [[1,1], [2,1]]
myHashMap.remove(2); // remove the mapping for 2, The map is now [[1,1]]
myHashMap.get(2); // return -1 (i.e., not found), The map is now [[1,1]]

    Constraints:

    • <code>0 <= key, value <= 10<sup>6</sup></code>

    • At most <code>10<sup>4</sup></code> calls will be made to put, get, and remove.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      MyHashMap()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Unit put(Integer key, Integer value)
      final Integer get(Integer key)
      final Unit remove(Integer key)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait