Package g0701_0800.s0706_design_hashmap

Class MyHashMap

  • public class MyHashMap
extends Object
    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:

    • 0 <= key, value <= 106
    • At most 104 calls will be made to put, get, and remove.

    • Constructor Detail

      • MyHashMap

        public MyHashMap()

    • Method Detail

      • put

        public void put​(int key,
                int value)

      • get

        public int get​(int key)

      • remove

        public void remove​(int key)