Jump to content
  • Advertisement

C++ Hacker Rank challenges. My understanding

This topic is 378 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I decided to take on competition and challenges across the internet. My place of choice at the moment is hacker rank. I'm stuck on hacker rank's 30 day challenge day 8.  I need to create a map key data structure for a phone book. The maps need to be the names of the people and the keys are their numbers. Does anyone know how to complete this challenge and could someone explain to me why test case 1 would fail with my code?


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

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int it = 0;
    int n;
    int number;
    string name;
    std::map<string,int> phoneBook;
    //Number of names + phone numbers
    cin >> n;
    //Fill in Map and keys
    while (it < n)
        cin >> name;
        cin >> number;
        if(phoneBook.insert(std::make_pair(name, number)).second != false)
           phoneBook.insert(std::make_pair(name, number));
    //Find the keys using the map
    for (int i = 0; i < n; i++)
        cin >> name;
        if(phoneBook.find(name) != phoneBook.end())
        else if(phoneBook.find(name) == phoneBook.end())
            cout<<"Not found"<<endl;
    return 0;


Share this post

Link to post
Share on other sites

Does Hacker Rank have a forum where you could post this question? If not, you should probably link to the question and/or provide the actual test case (if their site terms allow you to do so, which I'm not sure they do) so we can better assist you.

Share this post

Link to post
Share on other sites

Today, we're learning about Key-Value pair mappings using a Map or Dictionary data structure. Check out the Tutorial tab for learning materials and an instructional video!

Given  names and phone numbers, assemble a phone book that maps friends' names to their respective phone numbers. You will then be given an unknown number of names to query your phone book for. For each queried, print the associated entry from your phone book on a new line in the form name=phoneNumber; if an entry for  is not found, print Not found instead.

Note: Your phone book should be a Dictionary/Map/HashMap data structure.

Input Format

The first line contains an integer, , denoting the number of entries in the phone book. 
Each of the  subsequent lines describes an entry in the form of  space-separated values on a single line. The first value is a friend's name, and the second value is an -digit phone number.

After the  lines of phone book entries, there are an unknown number of lines of queries. Each line (query) contains a  to look up, and you must continue reading lines until there is no more input.

Note: Names consist of lowercase English alphabetic letters and are first names only.



Output Format

On a new line for each query, print Not found if the name has no corresponding entry in the phone book; otherwise, print the full  and  in the format name=phoneNumber.

Sample Input

sam 99912222
tom 11122222
harry 12299933

Sample Output

Not found


We add the following  (Key,Value) pairs to our map so it looks like this:


We then process each query and print key=value if the queried  is found in the map; otherwise, we print Not found.

Query 0: sam 
Sam is one of the keys in our dictionary, so we print sam=99912222.

Query 1: edward 
Edward is not one of the keys in our dictionary, so we print Not found.

Query 2: harry 
Harry is one of the keys in our dictionary, so we print harry=12299933.


Test case 1 has over 100000 inputs. Here is the link they gave me. I didn't see a forum but they do seem to have some sort of discussion section. This is usually my go to place but that might stem from admiration, regardless I will be exploring hacker rank now. 


Share this post

Link to post
Share on other sites

  • Advertisement

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!