Hello there, today we are going to solve Maps STL Hacker Rank Solution in C++.
Table Of Contents 👊
Objective
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++
#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <set>
#include <map>
#include <algorithm>
using namespace std;
int main() {
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 Sloth Coders. This tutorial is only for Educational and Learning Purpose.