Find duplicate string


Given an array of strings in which some strings are repeated,find the first repeating string

Given an array of strings find the first pair of string which is repeated

#include <bits/stdc++.h>
using namespace std;
int main(){
string arr[]={“name”,“class”,“address”,“class”,“name”,“anshika”,“city”};
int n=7;
int hash[7];
for(int i=0;i<n;i++)
unordered_map<string ,int> strings;
for(int i=0;i<n;i++){
for(int i=0;i<n;i++){


using namespace std;

// returns first repeated word
string findFirstRepeated(string s)
// break string into tokens
// and then each string into set
// if a word appeared before appears
// again, return the word and break

istringstream iss(s);
string token;

// hashmap for storing word and its count
// in sentence
unordered_map<string, int> setOfWords;

// store all the words of string
// and the count of word in hashmap

while (getline(iss, token, ' ')) {
    if (setOfWords.find(token) != setOfWords.end())             
        setOfWords[token] += 1;  // word exists
        // insert new word to set
        setOfWords.insert(make_pair(token, 1));        

// traverse again from first word of string s
// to check if count of word is greater than 1

// either take a new stream or store the words 
// in vector of strings in previous loop
istringstream iss2(s);
while (getline(iss2, token, ' ')) {
    int count = setOfWords[token];
    if (count > 1) {
        return token;

return "NoRepetition";


// driver program
int main()
string s(“Ravi had been saying that he had been there”);
string firstWord = findFirstRepeated(s);
if (firstWord != “NoRepetition”)
cout << "First repeated word :: "
<< firstWord << endl;
cout << “No Repetitionn”;
return 0;


// CPP program to find the first
// repeated character in a string
#include <bits/stdc++.h>
using namespace std;

// Returns first repeating character in str.
char firstRepeating(string &str)
// Creates an empty hashset
unordered_set h;

// Traverse the input array from left to right
for (int i=0; i<str.length(); i++)
    char c = str[i];

    // If element is already in hash set, update x
    // and then break
    if (h.find(c) != h.end())
        return c;

    else // Else add element to hash set

// If there was no repeated character
return '\0';


// Driver method to test above method
int main ()
string str = “geeksforgeeks”;
cout << firstRepeating(str);
return 0;


how to do without using any inbuilt data structure and just using array