Package g0101_0200.s0150_evaluate_reverse_polish_notation

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    150 - Evaluate Reverse Polish Notation\.

    Medium

    Evaluate the value of an arithmetic expression in Reverse Polish Notation.

    Valid operators are +, -, *, and /. Each operand may be an integer or another expression.

    Note that division between two integers should truncate toward zero.

    It is guaranteed that the given RPN expression is always valid. That means the expression would always evaluate to a result, and there will not be any division by zero operation.

    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

    Explanation: ((10 \* (6 / ((9 + 3) \* -11))) + 17) + 5

    = ((10 \* (6 / (12 \* -11))) + 17) + 5

    = ((10 \* (6 / -132)) + 17) + 5

    = ((10 \* 0) + 17) + 5

    = (0 + 17) + 5

    = 17 + 5

    = 22

    Constraints:

    • <code>1 <= tokens.length <= 10<sup>4</sup></code>

    • tokens[i] is either an operator: "+", "-", "*", or "/", or an integer in the range [-200, 200].

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Map<String, Function2<Integer, Integer, Integer>> getOp()
      final Integer evalRPN(Array<String> tokens)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait