Hacker Rank 30 days of code Day 8: Dictionaries and Maps

The problem:

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

Task
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 (in the form ) or  if there is no entry for .

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 , and the second value is an -digit .

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 letters and are first names only.

Constraints

Output Format

On a new line for each query, print  if the name has no corresponding entry in the phone book; otherwise, print the full  and  in the format .

Sample Input

3
sam 99912222
tom 11122222
harry 12299933
sam
edward
harry

Sample Output

sam=99912222
Not found
harry=12299933

Explanation

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

We then process each query and print  if the queried Key is found in the map, or otherwise.

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

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

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

The solution:

 #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 n, number;   
   cin >> n;  
   string name1, name2;  
   map<string, int> list;  
   for(int i=0;i<n;i++){  
     cin>>name1;  
     cin>>number;  
     cin.ignore(); //needed to ignore the space after the number, and bring to newline  
     list[name1]=number;  
   }  
   while(getline(cin,name2)){  
     if(list.find(name2) !=list.end()){  
       cout<< name2 << "=" <<list[name2]<<endl;  
     }  
     else   
       cout<<"Not found"<<endl;  
   }  
   return 0;  
 }