Basic Calculator
Given a string s representing a valid expression, implement a basic calculator to evaluate it, and return the result of the evaluation.
Given a string s representing a valid expression, implement a basic calculator to evaluate it, and return the result of the evaluation.
Given a string s which represents an expression, evaluate this expression and return its value.
Implement the RandomizedSet class...
Implement pow(x, n), which calculates x raised to the power n.
Given a signed 32-bit integer x, return x with its digits reversed.