Zad. 1
#include <iostream>

using namespace std;

int* createArr(int [], int);
void printArr(int [], int);
bool checkElem(int, int *, int);

int main()
{
    int n, index = 0;
    cout << "n = ";
    cin >> n;

    int arr[n];
    int result[n] = { 0 };

    createArr(arr, n);

    for(int i = 0; i < n; i++)
    {
        if(checkElem(i, arr, n))
        {
            if(index == 0)
            {
                result[index] = arr[i];
                index++;
            }
            else
            {
                bool flag = true;
                for(int j = 0; j < index; j++)
                {
                    if(result[j] == arr[i])
                        flag = false;
                }

                if(flag)
                {
                    result[index] = arr[i];
                    index++;
                }
            }
        }
    }

    printArr(result, n);
    return 0;
}

int* createArr(int arr[], int n)
{
    for(int i = 0; i < n; i++)
    {
        cout << "arr[" << i << "] = ";
        cin >> arr[i];
    }

    return arr;
}

void printArr(int arr[], int n)
{
    for(int i = 0; i < n; i++)
        cout << arr[i] << '\t';
    cout << endl;
}
bool checkElem(int index, int* arr, int n)
{
    int x = arr[index];
    for(int i = 0; i < n; i++)
    {
        if(x == arr[i] && index != i)
            return true;
    }
    return false;
}

Zad. 2
#include <iostream>
#include <stdlib.h>
#include <time.h>
using namespace std;
void createArr(int [], int);
void printArr(int [], int);
int* reverseArr(int*, int);

int main()
{
    int n;
    cout << "n = ";
    cin >> n;

    int * arr = new int[n];

    createArr(arr, n);
    printArr(arr, n);
    cout << '\n';

    arr = reverseArr(arr, n);
    printArr(arr, n);
    return 0;
}


void createArr(int arr[], int n)
{
    srand(time(0));

    for(int i = 0; i < n; i++)
    {
        arr[i] = rand() % 100 + 1;
    }
}

void printArr(int arr[], int n)
{
    for(int i = 0; i < n; i++)
        cout << arr[i] << '\t';
    cout << endl;
}

int* reverseArr(int* arr, int n)
{
    int * temp = new int[n];
    int index = 0;
    for(int i = n - 1; i >= 0; i--)
    {
        temp[index] = arr[i];
        index++;
    }

    return temp;
}
Zad. 3
#include <iostream>
#include <math.h>

using namespace std;

void enterTriangle(int **, int);
double calcArea(int *, int);
void printArr(int **, int);

int main()
{
    int n, row;
    cout << "n = ";
    cin >> n;

    int ** arr = new int*[n];
    for(int i = 0; i < n; i++)
        arr[i] = new int[3];

    enterTriangle(arr, n);
    printArr(arr, n);


    double s1, maxS = -1;
    maxS = calcArea(arr[0], 3);
    for(int j = 1; j < n; j++)
    {
        s1 = calcArea(arr[j], 3);
        if(s1 > maxS)
        {
            maxS = s1;
            row = j;
        }
    }

    cout << row + 1 << ": " << arr[row][0] << " "
         << arr[row][1] << " " << arr[row][2] << endl;
    cout << "Area: " << maxS << endl;
    return 0;
}

void enterTriangle(int ** triangles, int n)
{
    for(int i = 0; i < n; i++)
    {
        cout << "Enter triangle " << i + 1 << ": ";
        for(int j = 0; j < 3; j++)
        {
            cin >> triangles[i][j];
        }
    }
}
double calcArea(int * edges, int n)
{
    double res, p;
    p = (edges[0] + edges[1] + edges[2]) / 2;

    res = sqrt(p * (p - edges[0]) * (p - edges[1]) * (p - edges[2]));

    return res;
}
void printArr(int ** triangles, int n)
{
    for(int i = 0; i < n; i++)
    {
        cout << i + 1 << ": " << triangles[i][0] << " "
             << triangles[i][1] << " " << triangles[i][2] << endl;
    }
}