07. Design HashMap.cpp

/*
Design HashMap
==============

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
{
public:
  vector<int> hash;

  /** Initialize your data structure here. */
  MyHashMap()
  {
    hash = vector<int>(1000001, -1);
  }

  /** value will always be non-negative. */
  void put(int key, int value)
  {
    hash[key] = value;
  }

  /** Returns the value to which the specified key is mapped, or -1 if this map contains no mapping for the key */
  int get(int key)
  {
    return hash[key];
  }

  /** Removes the mapping of the specified value key if this map contains a mapping for the key */
  void remove(int key)
  {
    hash[key] = -1;
  }
};

/**
 * Your MyHashMap object will be instantiated and called as such:
 * MyHashMap* obj = new MyHashMap();
 * obj->put(key,value);
 * int param_2 = obj->get(key);
 * obj->remove(key);
 */