Section 1Understand Problem
Section 01
Understand the problem
Restate the problem precisely. Interviewers reward candidates who pause, define the contract, and name the guarantees before coding.
Problem statement
You are given an array of strings `tokens` that represents an arithmetic expression in Reverse Polish Notation. Evaluate the expression. Return *an integer that represents the value* of the expression. Note that division between two integers should truncate toward zero. The given RPN expression is always valid.
Example
tokens = ["2", "1", "+", "3", "*"] → 9
Constraints
1 ≤ tokens.length ≤ 10⁴ · tokens[i] is either an operator or an integer in [-200, 200]
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