LeetCode 150 Evaluate Reverse Polish Notation - Problem Statement

Evaluate an arithmetic expression in Reverse Polish Notation (RPN).

In RPN, operators come after their operands. ["2", "1", "+", "3", "*"] means (2 + 1) * 3 = 9.

Valid operators are +, -, *, /. Division truncates toward zero.

With ["4", "13", "5", "/", "+"], the answer is 6. Compute 13 / 5 = 2, then 4 + 2 = 6.

Constraints: $1 \le$ tokens $\le 10^4$. Input always forms a valid expression.