20. Evaluate the following postfix expression using a stack and show the contents of stack after execution of each operation :
20, 45, +, 20, 10, -, 15, +, *
(where A = 5, B = 3, C = 5, D= 4, and E= 2) Algo : 1) If operand is encountered, push it onto Stack [End If] 2) If operator is encountered, Pop two elements i) A -> Top element ii) B-> Next to Top element iii) Evaluate B operator A push B