Package g0201_0300.s0227_basic_calculator_ii

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    227 - Basic Calculator II\.

    Medium

    Given a string s which represents an expression, evaluate this expression and return its value.

    The integer division should truncate toward zero.

    You may assume that the given expression is always valid. All intermediate results will be in the range of <code>-2<sup>31</sup>, 2<sup>31</sup> - 1</code>.

    Note: You are not allowed to use any built-in function which evaluates strings as mathematical expressions, such as eval().

    Example 1:

    Input: s = "3+2\*2"

    Output: 7

    Example 2:

    Input: s = " 3/2 "

    Output: 1

    Example 3:

    Input: s = " 3+5 / 2 "

    Output: 5

    Constraints:

    • <code>1 <= s.length <= 3 * 10<sup>5</sup></code>

    • s consists of integers and operators ('+', '-', '*', '/') separated by some number of spaces.

    • s represents a valid expression.

    • All the integers in the expression are non-negative integers in the range <code>0, 2<sup>31</sup> - 1</code>.

    • The answer is guaranteed to fit in a 32-bit integer.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Integer calculate(String s)

      • Methods inherited from class java.lang.Object

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