| 15 | } |
| 16 | |
| 17 | int dequeue(){ |
| 18 | if(s1.empty() && s2.empty()){ |
| 19 | cout << "Error" << endl; |
| 20 | exit(0); |
| 21 | } |
| 22 | //REVERESE STACK1 BY USING STACK2 |
| 23 | if(s2.empty()){ |
| 24 | while(!s1.empty()){ |
| 25 | s2.push(s1.top()); |
| 26 | s1.pop(); |
| 27 | } |
| 28 | } |
| 29 | //THEN SIMPLY POPPING THE FIRST ELEMENT OF STACK2, i.e. THE LAST ELEMENT OF STACK1 |
| 30 | int topval = s2.top(); |
| 31 | s2.pop(); |
| 32 | |
| 33 | return topval; |
| 34 | } |
| 35 | |
| 36 | // RETURNS TRUE IF BOTH STACKS ARE EMPTY |
| 37 | bool empty(){ |