The results

  2  6 18 20 16 11  9 12 13  3max_value: 20min_value: 2comp_times: 17
 14  5  1  2 17  4 15  7  7 16max_value: 17min_value: 1comp_times: 19
  1  1  3  9 17  7 13  9 20 15max_value: 20min_value: 1comp_times: 16
  1  1  8 16  3 10 18 18 10  6max_value: 18min_value: 1comp_times: 17
 14 18  7 16 17  6 20 12 14 18max_value: 20min_value: 6comp_times: 18
  4 17 12 12 12  5  4 17 15  7max_value: 17min_value: 4comp_times: 19
 19  4 14  4 10 18 15 20  4 15max_value: 20min_value: 4comp_times: 19
 14  6  8  4  8 17 12  9 12 16max_value: 17min_value: 4comp_times: 19
  9 17 20  8 20 16  5 12 12  9max_value: 20min_value: 5comp_times: 18
 17  1  1  4  4 11  8 13 20  4max_value: 20min_value: 1comp_times: 19
average_comp_times: 18.1

 The corresponding codes:

//get the least comparing times to get the minimum and maximum values
#include <iostream>
#include <iomanip>
#include <ctime>
#include <cstdlib>
const int N = 10;
void randa(int a[]);
void disp_array(int a[]);
int get_min_max(int a[], int &min, int &max);
int main()
{
    srand((unsigned)time(NULL));
    int a[N];
    double sum_comp_times = 0.0;
    for (int i = 0; i < 10; i++) {
        randa(a);
        disp_array(a);
        //obtain the minimum and maximum values in the random array
        int max_value = 0;
        int min_value = 0;
        int comp_times = 0;
        comp_times = get_min_max(a, min_value, max_value); 
        std::cout << "max_value: " << max_value << std::setw(3);
        std::cout << "min_value: " << min_value << std::setw(3);
        std::cout << "comp_times: " << comp_times << std::endl;
        sum_comp_times += comp_times;
    }
    double average_comp_times = sum_comp_times / 10.0;
    std::cout << "average_comp_times: " << average_comp_times << std::endl;
}
void randa(int a[])
{
    for (int i = 0; i < N; i++)
    {
        a[i] = rand() % 20 + 1;
    }
}
void disp_array(int a[])
{
    for (int i = 0; i < N; i++)
    {
        std::cout << std::setw(3) << a[i];
    }
}
int get_min_max(int a[], int &min, int &max)
{
    int comp_times =0; //tag the comparing time to get the max and min values
    int temp_min = a[0];  //tag the temporary min value in array at present
    int temp_max = a[0];  //tag the temporary max value in array at present
    for (int i = 0; i < N; i++) {
        ++comp_times;
        if(a[i] > temp_max) 
            temp_max = a[i];
        else{
            ++comp_times;
            if (a[i] < temp_min) 
                temp_min = a[i];
        }
    }
    min = temp_min;
    max = temp_max;
    return comp_times;
}