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Evaluate Reverse Polish Notation

Medium
VerifiedStack~22 min

Given tokens in reverse Polish notation, evaluate the expression and return the integer result. Operators are +, -, *, /; each pops its two operands. Division truncates toward zero.

The input arrives as a single array tokens. Push operands on a stack; on an operator, pop two and push the result.

Examples

in["2", "1", "+", "3", "*"]
out9

(2 + 1) * 3 = 9.

in["4", "13", "5", "/", "+"]
out6

4 + (13 / 5) = 4 + 2 = 6.

Constraints

  • 1 ≤ tokens.length ≤ 10⁴
  • Each token is an operator (+ - * /) or an integer.
  • Division truncates toward zero.

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