Program : Remove duplicates from an array, keeping only the first occurrence of each element in C++.

Solution :

#include <iostream>
using namespace std;

void removeDuplicates(int array[], int& size) {
    int newSize = 0, i;
    for (i = 0; i < size; i++) {
        bool isDuplicate = false;
        for (int j = 0; j < newSize; j++) {
            if (array[i] == array[j]) {
                isDuplicate = true;
                break;
            }
        }
        if (!isDuplicate) {
            array[newSize++] = array[i];
        }
    }
    size = newSize;
}

void printArray(const int array[], int size) {
    for (int i = 0; i < size; i++) {
        cout << array[i] << " ";
    }
}

int main() {
    const int MAX_SIZE = 100;
    int size, i;
    int arr[MAX_SIZE];

    cout << "Enter the size of the array: ";
    cin >> size;

    cout << "Enter the elements of the array: ";
    for (i = 0; i < size; i++) {
        cin >> arr[i];
    }

    removeDuplicates(arr, size);

    cout << "Array after removing duplicates: ";
    printArray(arr, size);

    return 0;
}

Output :

Enter the size of the array: 10
Enter the elements of the array: 2 
4 
6 
2 
8 
6 
10 
4 
12 
8
Array after removing duplicates: 2 
4 
6 
8 
10 
12

Dry Run :

Let’s walk through the code written inside the removeDuplicates() function with the following inputs:

• Array: [2, 4, 6, 2, 8, 6, 10, 4, 12, 8]

The duplicates are removed from the array, and the resulting array is [2, 4, 6, 8, 10, 12].

Want to practice more problems involving Array 1-D ? Click here.