Генерация уникальных чисел

for(int i=0; i<100; ++i)

#include <iostream>
#include <algorithm>
 
const std::size_t SIZE = 20;
 
int main ()
{
    int mas [SIZE];
    for (std::size_t i=0; i<SIZE; ++i)
        mas [i] = i+1;
    std::random_shuffle (mas,mas+SIZE);
    for (std::size_t i=0; i<SIZE; ++i)
        std::cout << mas[i] << " ";
    return 0;
}

#include <iostream>
#include <chrono>
#include <random>
#include <algorithm>
#include <iterator>
#include <unordered_set>
 
using namespace std;
 
int main ()
{
    mt19937 gen(chrono::system_clock::now().time_since_epoch().count());
    uniform_int_distribution<int> distr(0, 100000);
    const int unique_requested = 100;
    unordered_set<int> unique_values(100);
    while (unique_values.size() < unique_requested)
        unique_values.insert( distr(gen) );
    cout << unique_requested << " unique values:\n";
    copy( begin(unique_values), end(unique_values),
                ostream_iterator<int>(cout, ", "));
    return 0;
}

#include <iostream>
#include <algorithm>
 
const int min = -5;
const int max = +5;
const std::size_t SIZE = max-min;
 
int main ()
{
    int mas [SIZE];
    for (std::size_t i=0; i<SIZE; ++i)
        mas [i] = i+1+min;
    std::random_shuffle (mas,mas+SIZE);
    for (std::size_t i=0; i<SIZE; ++i)
        std::cout << mas[i] << " ";
    return 0;
}