Lab1 - Pb7

#include <iostream>
using namespace std;

int x[10], maxx;

int numar(int a[10], int x[10], int c)
{
    int nr = 0;
    for (int i = 0; i < c; i++)
        nr = nr * 10 + a[x[i]];
    return nr;
}

void back(int k, int c, int a[], int n)
{
    if (k == c)
    {
        int nr = numar(a, x, c);
        if (nr > maxx) maxx = nr;
    }
    for (int i = n - 1; i >= 0; i--)
        if ((k - 1 >= 0 && i < x[k - 1]) || k == 0)
        {
            x[k] = i;
            if (k < c)
                back(k + 1, c, a, n);
        }
}

int main()
{
    int n, a[10], k;
    cin >> n >> k;
    int i = 0;
    while (n)
    {
        a[++i] = n % 10;
        n = n / 10;
    }
    n = i;
    back(0, n - k, a, n);
    cout << maxx;
    return 0;
}