Package g0101_0200.s0150_evaluate_reverse_polish_notation

Class Solution

java.lang.Object
g0101_0200.s0150_evaluate_reverse_polish_notation.Solution
public class Solution extends java.lang.Object
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:

  • 1 <= tokens.length <= 104
  • tokens[i] is either an operator: "+", "-", "*", or "/", or an integer in the range [-200, 200].

  • Constructor Summary

    Constructors
    Constructor
    Description
    Solution()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    evalRPN(java.lang.String[] tokens)
     

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • evalRPN

      public int evalRPN(java.lang.String[] tokens)