Evaluate Expression

Given a string tokens representing an arithmetic expression in Reverse Polish Notation (RPN), evaluate it and return the result as an integer.

Valid operators are +, -, *, and /. Each operand may be an integer or another expression. Division between two integers should truncate toward zero. You may assume the input is always a valid RPN expression and that evaluation never causes division by zero.

Example 1

Input: tokens = ["2", "1", "+", "3", "*"]
Output: 9
Explanation: ((2 + 1) * 3) = 9

Example 2

Input: tokens = ["4", "13", "5", "/", "+"]
Output: 6
Explanation: (4 + (13 / 5)) = 6

Example 3

Input: tokens = ["10", "6", "9", "3", "+", "-11", "*", "/", "*", "17", "+", "5", "+"]
Output: 22

Constraints

• 1 <= tokens.length <= 10^4
• Each token is either an operator (+, -, *, /) or an integer in the range [-200, 200].