Please remember, there are space(s) between operands/operators in the ex[1]pression. So your solution needs to think of this aspect.

You will solve the problem as stated below:-

(1) [Design a simple calculator that helps you solve the expression

given.

Please be reminded that you need to design the calculator and not use

in-built math methods from the programming language library to solve

the expression. Also at the end of the program as a comment mention the time and space complexity of your solution. Time and space complexity

Post-fix String Expression (Example) Scan '+', it's an operator, pop two operands from stack, apply the + operator on operands, we get 3+2 which results in 5. We push the result 5' to stack. The stack now becomes '5'. Scan '9', it's a number, we push it to the stack. The stack now becomes 5 9'. Scan '-', it's an operator, pop two operands from stack, apply the operator on operands, we get 5 - 9 which results in -4. We push the result -4' to the stack. The stack now becomes '-4'. There are no more elements to scan, we return the top element from the stack (which is the only element left in a stack) Test Cases Check for the following: Valid Input (numbers) Valid Operators Empty Input No operator in input Difference between 1, 2, and/or 3 digit number (think of how to use space character)