g0701_0800.s0706_design_hashmap

Class MyHashMap

java.lang.Object

g0701_0800.s0706_design_hashmap.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 Summary

Constructors

Constructor and Description
MyHashMap()

Method Summary

Modifier and Type	Method and Description
int	get(int key)
void	put(int key, int value)
void	remove(int key)

Methods inherited from class java.lang.Object

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

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)