# Maps-STL in C++ | HackerRank Solution

Hello coders, today we are going to solve Maps-STL HackerRank Solution in C++.

## Problem

Maps are a part of the C++ STL.Maps are associative containers that store elements formed by a combination of a key value and a mapped value, following a specific order.The mainly used member functions of maps are:

• Map Template:
``std::map <key_type, data_type>``
• Declaration:
``map<string,int>m; //Creates a map m where key_type is of type string and data_type is of type int.``
• Size:
``int length=m.size(); //Gives the size of the map.``
• Insert:
``m.insert(make_pair("hello",9)); //Here the pair is inserted into the map where the key is "hello" and the value associated with it is 9.``
• Erasing an element:
``m.erase(val); //Erases the pair from the map where the key_type is val.``
• Finding an element:
``````map<string,int>::iterator itr=m.find(val); //Gives the iterator to the element val if it is found otherwise returns m.end() .
Ex: map<string,int>::iterator itr=m.find("Maps"); //If Maps is not present as the key value then itr==m.end().``````
• Accessing the value stored in the key:
``To get the value stored of the key "MAPS" we can do m["MAPS"] or we can get the iterator using the find function and then by itr->second we can access the value.``

You are appointed as the assistant to a teacher in a school and she is correcting the answer sheets of the students.Each student can have multiple answer sheets.So the teacher has Q queries:

1 X Y :Add the marks Y to the student whose name is X.
2 X: Erase the marks of the students whose name is X.
3 X: Print the marks of the students whose name is X. (If X didn’t get any marks print 0.)

## Input Format

The first line of the input contains Q where Q is the number of queries. The next Q lines contain 1 query each.The first integer, type of each query is the type of the query.If query is of type 1, it consists of one string and an integer X and Y where X is the name of the student and Y is the marks of the student.If query is of type 2 or 3,it consists of a single string X where X is the name of the student.

## Constraints

• 1 <= Q <= 10^5
• 1 <= type <= 3
• 1 <= |X| <= 6
• 1 <= Y <= 10^3

## Output Format

For queries of type 3 print the marks of the given student.

Sample Input

``````7
1 Jesse 20
1 Jess 12
1 Jess 18
3 Jess
3 Jesse
2 Jess
3 Jess``````

Sample Output

``````30
20
0``````

## Solution – Maps-STL in C++

### C++

```#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <set>
#include <map>
#include <algorithm>
using namespace std;

int main() {
/* Enter your code here. Read input from STDIN. Print output to STDOUT */
map<string,int>s;

int q;
cin>>q;

for(int i=0;i<q;i++)
{
int t,n,m;
cin>>t;
switch(t)
{
case 1:
{
string name;
int marks;
cin>>name>>marks;
map<string,int>::iterator itr=s.find(name);
if(itr==s.end())
s.insert(make_pair(name,marks));
else
itr->second+=marks;
break;
}
case 2:
{
string name;
cin>>name;
s.erase(name);
break;
}
case 3:
{
string name;
cin>>name;
map<string,int>::iterator itr=s.find(name);
if(itr==s.end())
cout<<"0"<<endl;
else
cout<<itr->second<<endl;
break;
}
}
}
return 0;
}```

Disclaimer: The above Problem (Maps-STL) is generated by Hacker Rank but the Solution is Provided by CodingBroz. This tutorial is only for Educational and Learning Purpose.