void find_dequeable(unordered_set<string>& ds, Deque<T> in,
Deque<T> dq = Deque<T>(), Deque<T> out = Deque<T>()) {
if (in.empty() && dq.empty()) { /* out is full */
string setstr = out.str();
ds.erase(setstr);
return;
}
if (!in.empty()) {
/* push front, back to deque */
Deque<T> in_new1(in), in_new2(in);
Deque<T> dq_new1(dq), dq_new2(dq);
Deque<T> out_new1(out), out_new2(out);
dq_new1.push_front(in_new1.pop_front());
dq_new2.push_back(in_new2.pop_front());
find_dequeable(ds, in_new1, dq_new1, out_new1);
find_dequeable(ds, in_new2, dq_new2, out_new2);
}
if (!dq.empty()) { /* pop front, back from deque */
Deque<T> in_new3(in), in_new4(in);
Deque<T> dq_new3(dq), dq_new4(dq);
Deque<T> out_new3(out), out_new4(out);
/* input does not change */
out_new3.push_front(dq_new3.pop_front());
out_new4.push_front(dq_new4.pop_back());
find_dequeable(ds, in_new3, dq_new3, out_new3);
find_dequeable(ds, in_new4, dq_new4, out_new4);
}
}
int main(int argc, char *argv[]) {
ofstream file;
int elems[] = { 1, 2, 3, 4, 5 }; /* input elements */
unordered_set<string> perms; /* permutations of input */
Deque<int> input;
input.insert(elems, elems+5);
file.open("output.txt");
do {
Deque<int> temp;
temp.insert(elems, elems+5);
perms.insert(temp.str());
} while (next_permutation(elems, elems+5));
find_dequeable(perms, input);
for (unordered_set<string>::iterator it = perms.begin();
it != perms.end(); ++it)
file << *it << endl;
file.close();
return 0;
}
