/* Reverse a list element by element without using a further variable except list Example: List = 1,2,3 output: 123 132 321 edit:or output 123 312 321 https://www.sololearn.com/post/267892/?ref=app */ #include #include #include using namespace std; // display function() auto print_list=[](auto const& lst){ // can't escape the variable e, it is // used only for display for(auto e : lst) cout << e << ' '; cout << "\n\n"; }; #if 0 // make this 1 if you want to compile this version int main() { deque l{1,2,3,4,5,6,7,8,8,9}; cout << "Original List\n"; print_list(l); // add -1 as reference for terminating // condition l.emplace_back(-1); while(l[0] != -1) { // find the index of -1 // get the element at 1 pos before that // index and append it at back l.emplace_back(*(find(l.begin(), l.end(),-1)-1)); // again find the index of -1 and erase // the previous version l.erase(find(l.begin(), l.end(),-1)-1); } l.pop_front(); cout << "Reversed List\n"; print_list(l); } #endif #if 1 // make this 0 if you want to compile previous version int main() { deque l{1,2,3,4,5,6,7,8,8,9}; cout << "Original List\n"; print_list(l); // add 0 at front act as counter l.push_front(0); // go till half the list size while(l.front()<(int)l.size()/2){ // swap element at index l.front()+1 with the last element swap(l[l.front()+1], l[l.size()-l.front()-1]); l.front()++; } // remove the counter variable l.pop_front(); cout << "Reversed List\n"; print_list(l); } #endif

[Challenge] Oma'sList_reverse.cpp