Check duplicates in a stream of strings

Given an array arr[] of strings containing the names of employees in a company. Assuming that the names are being entered in a system one after another, the task is to check whether the current name is entered for the first time or not.

Examples:

Input: arr[] = {“geeks”, “for”, “geeks”}
Output:
No
No
Yes

Approach: Create an unordered_set to store the names of the employees and start traversing the array, if the current name is already present in the set then print Yes else print No and insert it into the set.

Below is the implementation of the above approach:

// C++ implementation of the approach #include <bits/stdc++.h> using namespace std;    // Function to insert the names // and check whether they appear // for the first time void insertNames(string arr[], int n) {        // To store the names     // of the employees     unordered_set<string> set;     for (int i = 0; i < n; i++) {            // If current name is appearing         // for the first time         if (set.find(arr[i]) == set.end()) {             cout << "No\n";             set.insert(arr[i]);         }         else {             cout << "Yes\n";         }     } }    // Driver code int main() {     string arr[] = { "geeks", "for", "geeks" };     int n = sizeof(arr) / sizeof(string);        insertNames(arr, n);        return 0; }

Output:

No
No
Yes

// Java implementation of the approach import java.util.*;    class GFG  {    // Function to insert the names // and check whether they appear // for the first time static void insertNames(String arr[], int n) {        // To store the names     // of the employees     HashSet<String> set = new HashSet<String>();     for (int i = 0; i < n; i++)      {            // If current name is appearing         // for the first time         if (!set.contains(arr[i]))         {             System.out.print("No\n");             set.add(arr[i]);         }         else          {             System.out.print("Yes\n");         }     } }    // Driver code public static void main(String[] args) {     String arr[] = { "geeks", "for", "geeks" };     int n = arr.length;        insertNames(arr, n); } }    // This code contributed by PrinciRaj1992

Output:

No
No
Yes

# Python3 implementation of the approach    # Function to insert the names  # and check whether they appear  # for the first time  def insertNames(arr, n) :         # To store the names      # of the employees      string = set();            for i in range(n) :            # If current name is appearing          # for the first time          if arr[i] not in string :             print("No");              string.add(arr[i]);                 else :              print("Yes");         # Driver code  if __name__ == "__main__" :         arr = [ "geeks", "for", "geeks" ];      n = len(arr);         insertNames(arr, n);     # This code is contributed by AnkitRai01

Output:

No
No
Yes