# Program to find the first repeating element in an array of integers in C++

## C++ program to find the first repeating element in an array of integers

Example:

Input: {5, 15, 20, 5, 6, 10, 15, 10}

Output: 5

### # Algorithm

1. Take an array as input and store its size in a variable `n`.
2. Start a loop from `i` = 0 to `i` < `n`, which will select each element from the array.
3. Inside the loop, start a second loop from `j` = `i` + 1 to `j` < `n` to traverse ahead and check for duplicates.
4. If a duplicate is found (i.e., `array[i]` is equal to `array[j]`), print the first repeating integer and return 0.
5. Else, print "No integer repeated".

Code:

``````#include <bits/stdc++.h>
using namespace std;

int main() {
int array[100], n, i;
cout << "Enter number of elements: ";
cin >> n;
cout << "\nEnter elements: ";
for (i = 0; i < n; i++)
cin >> array[i];

cout << "Original array: ";

for (int i = 0; i < n; i++)
cout << array[i] << " ";

// selecting an element

for (int i = 0; i < n; i++)
// traversing to check repetition
for (int j = i + 1; j < n; j++)
if (array[i] == array[j]) {
cout << "\nFirst repeating integer is " << array[i];
return 0;
}

cout << "No integer repeated\n";
return 0;
}

``````

Output

``````Enter number of elements: 5

Enter elements: 1 2 3 4 5
Original array: 1 2 3 4 5
No integer repeated

``````

Time Complexity: O(N2)