Hashmap takes up too much memory in c++ because there are too few basic types and too many objects.

Solution:

1. Import the hash_map class library in stl.

# include & lthash _ map & gt

Use namespace std

Use the namespace stdext

2.hash_map is an aggregation class.

It inherits from the _Hash class, including a vector, a list and a pair, where the vector is used to save bucket, the list is used for conflict handling, and the pair is used to save key->; Value structure, brief pseudo code is as follows:

class hash _ map & ltclass _Tkey，class _ Tval & gt

{

Private:

Typedef pair & lt_Tkey, _ Tval & gt hash pair;

Typedef list & lt hash pair & gthash _ list

Typedef vector & lthash _ list & gt hash _ table;

};

3. Examples of usage:

Hash _ map & ltint, int> intash;

in hash[ 1]= 123；

in hash[2]= 456；

int val = in hash[ 1]；

int val = in hash[2]；