Question

I have to modify the following code to:

1. Use the unique algorithm to reduce the array to unique values

2. Use the copy algorithm to display the unique results.

#include<iostream>

#include<vector>

#include<algorithm>

using namespace std;

int main() {

    //creating an array of 20 integers

    int array[20];

    //creating an empty vector

    vector<int> vec;

    //input from end user to get 20 ints and a for loop to interate through 20

    cout << "Enter 20 integers:" << endl;

    for (int i = 0; i < 20; i++) {

        cin >> array[i];

    }
    //sorting them

    sort(array, array + 20);

    //using unique_copy algorithm and a back_inserter, copying and adding each

    //unique value from the array to vector

    unique_copy(array, array + 20, back_inserter(vec));

    //displaying the unique values.

    cout << "The unique values are: " << endl;

    for (int i = 0; i < vec.size(); i++) {

        cout << vec[i] << " ";

    }

    cout << endl;

    return 0;

Answer 1

#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;

int main() {

        //creating an array of 20 integers
        int array[20];

        //creating an empty vector
        vector<int> vec;

        //input from end user to get 20 ints and a for loop to interate through 20
        cout << "Enter 20 integers:" << endl;

        for (int i = 0; i < 20; i++) {
                cin >> array[i];
        }
        
        //sorting them
        sort(array, array + 20);
        
        // use unique algorithm to reduce array to unique value
        auto it = unique(array,array+20);
        
        // use copy algorithm
        copy(array,it,back_inserter(vec));
        
        // alternatively you can also do
        // copy(array,unique(array,array+20);,back_inserter(vec));

        //displaying the unique values.
        cout << "The unique values are: " << endl;
        for (int i = 0; i < vec.size(); i++) {
                cout << vec[i] << " ";
        }
        cout << endl;
        return 0;
}

Code screenshot:

Code output screenshot:

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There are two ways to do:

1)
   auto it = unique(array,array+20);
   copy(array,it,back_inserter(vec));
  

2)
   copy(array,unique(array,array+20);,back_inserter(vec));

YOu can use any one.

Code along with it's output and screenshot have been added. Please refer to them

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For any query comment.