Problem: Evaluate Reverse Polish Notation
Explore how to evaluate arithmetic expressions in Reverse Polish Notation using a stack. Learn key operations of pushing operands and applying operators with efficient O(n) time complexity. This lesson helps you understand stack usage for real-world expression evaluation and prepares you to implement similar problems in C++.
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Statement
You are given an array of strings tokens representing a valid arithmetic expression in Reverse Polish Notation (RPN). Your task is to evaluate the expression and return an integer representing the value of the expression.
Note: The valid operators are
'+','-','*', and'/'.
Each operand may be an integer or another expression.
Division between two integers always truncates toward zero.
There will not be any division by zero.
The input is guaranteed to represent a valid arithmetic expression in Reverse Polish Notation.
The answer and all intermediate calculations can be represented in a‑bit integer.
Constraints:
tokens.lengthtokens[i]is either an operator:"+", ...