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.