MAP

Map i.e., Hash Table is a data structure which stores mapped values of given key values, map Library in c++ is somewhat similar to dictionary in python

Some basic functions of map are insertion of key-value pair,deletion of given key value,iteration of data structure

HEADER FILE

use

#include<map>

INITIATING

• mapping of integer keys to integer values map<int,int> m;

• mapping of string keys to integer values map<string,int> m;

OPERATIONS

• Insertion : m.insert({key,val});

• Deletion : m.erase(key);

• Iteration :

  for(auto it=m.begin();it!=m.end();++it){
    cout << it->first << ' ' << it->second << '\n' ;	
  }
  

Note : In the above code , the keyword auto automates the task of determining the suitable data type of variable it , the data type of “it” is an iterator to stl::map i.e., map<int,int>::iterator. It does so in compile time , hence not effecting run time of program . it->first : key , it->second : mapped value of given key one key can never map to 2 different values

• Accessing mapped value : cout << m[key] ;
• Size of Hash Map : cout << m.size() ;
• Check if a key is present in map : m.find(key) returns m.end() if key not present in map else iterator to key is returned

Time Complexity

Insertion , Deletion , Accessing mapped value take O(log N) time as hash map is implemented using balanced binary trees

practice

For a better understanding try solving this problem Though this might be solved by some other techniques , try solving this using hash maps

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