Question

Which of the following is valid reverse polish expression?

(a) a op b

(b) op a b

(c) a b op

(d) both op a b and a b op

This interesting question is from Application of Stacks topic in chapter Application of Stacks of Data Structures & Algorithms I

This question was posed to me during a job interview.

Answer 1

The correct choice is (c) a b op

The best explanation: The postfix expression is also known as the reverse polish expression. In postfix expressions, the operators come after the operands. So, the correct expression is a b op and hence a b op is correct.