/*⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️*\ Programmed by: __ __ ___ _ _ _ __ _ ®© | \ / |/ \| |_| | / \ | \ | | | |\V/| | O | _ |/ Δ \| |\\| | |_| V |_|\___/|_| |_|_/ \_|_| \__| INSPIRED FROM MANY, MADE BY ME😅😉 \*⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️🔸⚜️*/ /*!!!!!MUST SEE THE OUTPUT!!!!!*/ #include using namespace std; namespace itertools { template bool next_combination( const Itr, Itr, const Itr ); vector permutations(string); vector combinations( string, int ); } int main() { auto s = "ABCD"s; cout<< "Permutation(shuffling)" << " of \"ABCD\" are:\n"; auto p = itertools::permutations(s); for (auto e : p) cout << e << endl; cout<< "No. of Permutations of " << "\"ABCD\" is: " << p.size() << endl << string(35, '_') << "\n\nCombination of \'ABCD\'" << " (selecting any 2 at a time) " << "are:\n"; auto c = itertools::combinations(s, 2); for (auto e : c) cout<< e[0] << " and " << e[1] << endl; cout<< "No. of Combinations of " << "\'ABCD\' when selected 2 at " << "a time is: " << c.size(); } template bool itertools :: next_combination( const Itr first, Itr k, const Itr last ) { if ( first == last or first == k or last == k ) { return false; } auto itr1 = first; auto itr2 = last; ++itr1; if (last == itr1) return false; itr1 = last; --itr1; itr1 = k; --itr2; while (first != itr1) { if (*--itr1 < *itr2) { auto j = k; while (not(*itr1 < *j)) ++j; iter_swap(itr1, j); ++itr1; ++j; itr2 = k; rotate(itr1, j, last); while (last != j) { ++j; ++itr2; } rotate(k, itr2, last); return true; } } rotate(first, k, last); return false; } vector itertools :: permutations( string s ) { vector vs {}; sort(s.begin(), s.end()); do { vs.push_back(s); } while ( next_permutation( s.begin(), s.end() ) ); return vs; } vector itertools :: combinations( string s, int n ) { vector vs {}; do { vs.push_back(string( s.begin(), s.begin() + n )); } while ( next_combination( s.begin(), s.begin() + n, s.end() ) ); return vs; }

Example of P&C