gen cuv 3/11/2020

#include <iostream>
#include<cstring>
using namespace std;
int st[5], card[5], n;
char s[4][5];

void tipar(int k) {
    for (int i = 1; i <= k; i++)
        cout << s[i][st[i] - 1];
    cout << endl;
}

int valid(int k) {
    for (int i = 1; i < k; i++)
        if (s[i][st[i] - 1] == s[k][st[k] - 1])
            return 0;
    return 1;
}

int sol(int k) {
    return k == n;
}

void bktr() {
    int k = 1;
    st[k] = 0;
    while (k > 0) {
        if (st[k] < card[k]) {
            st[k]++;
            if (valid(k)) {
                if (sol(k))
                    tipar(k);
                else {
                    k++;
                    st[k] = 0;
                }
            }
        }
        else
            k--;
    }
}

int main() {
    n = 4;
    strcpy(s[1], "aeiou"), card[1] = strlen(s[1]);
    strcpy(s[2], "prst"), card[2] = strlen(s[2]);
    strcpy(s[3], "bmrtv"), card[3] = strlen(s[3]);
    strcpy(s[4], s[1]), card[4] = card[1];
    bktr();
    return 0;
}