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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.

 

Follow up: Please do not use the built-in HashMap library.

Related Topics

[Design] [Hash Table]

Similar Questions

1. Design HashSet (Easy)

Documentation

Index

• type MyHashMap
  • func Constructor() MyHashMap
  • func (this *MyHashMap) Get(key int) int
  • func (this *MyHashMap) Put(key int, value int)
  • func (this *MyHashMap) Remove(key int)

Types

type MyHashMap

type MyHashMap struct {
	// contains filtered or unexported fields
}

func Constructor

func Constructor() MyHashMap

* Initialize your data structure here.

func (*MyHashMap) Get

func (this *MyHashMap) Get(key int) int

* Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key

func (*MyHashMap) Put

func (this *MyHashMap) Put(key int, value int)

* value will always be non-negative.

func (*MyHashMap) Remove

func (this *MyHashMap) Remove(key int)

* Removes the mapping of the specified value key if this map contains a mapping for the key