Uber Phone Screen | Basic Calculator (Variation)

Round 1

Questions: This is a variation on the Basic Calculator where we essentially are thinking about parsing the input in a pre-order manner [sign, operand1, operand2].

• Suggested a recursive solution, was pressed to determine if linear was possible.
• Came to an approach with two stacks (with a hint to think about how we decide to add or subtract two operands in the string).

Input/Output Examples:

# Parse strings that for a simple language as follows :
# input -> "add(1,3)" output -> 4
# input -> "sub(1,3)" output -> -2
# Input -> “add(3,     add(3, 2))” ->  8
# Input -> “           add(3, sub(3, add(3, 2)))        ” ->  1
# Input -> “add( bad,2342)” -> return exception “syntax error at position 6 for "bad" in the string”