Consider a stack $S$ and a queue $Q$. Both of them are initially empty and have the capacity to store ten elements each. The elements $1, 2, 3, 4,$ and $5$ arrive one by one, in that order. When an element arrives, it is assigned either to $S$ (pushed on $S$) or to $Q$ (enqueued to $Q$). Once all the five elements are stored, the output is generated in two steps. First, stack $S$ is emptied by popping all elements. Then queue $Q$ is emptied by dequeueing all elements. The output obtained by following this process is $4\ 3\ 1\ 2\ 5$ . Given the output, the objective is to predict whether an element was assigned to $S$ or $Q$. Which of the following options is/are possible valid assignment(s) of the elements? *Note:* In the options, the notation $xS$ denotes that element $x$ was assigned to $S$ and $yQ$ denotes that element $y$ was assigned to $Q$.

Consider a stack S and a queue Q. Both of them are initially empty and have the capacity to store ten elements each. The elements 1, 2, 3, 4, and 5 arrive one by one, in that order. When an element arrives, it is assigned either to S (pushed on S) or to Q (enqueued to Q). Once all the five elements are stored, the output is generated in two steps. First, stack S is emptied by popping all elements. Then queue Q is emptied by dequeueing all elements. The output obtained by following this process is 4\ 3\ 1\ 2\ 5 . Given the output, the objective is to predict whether an element was assigned to S or Q. Which of the following options is/are possible valid assignment(s) of the elements? *Note:* In the options, the notation xS denotes that element x was assigned to S and yQ denotes that element y was assigned to Q.

Topic-wise GATE CS PYQs with verified steps