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Calculator with Parentheses

Certification: Intermediate Level Accuracy: 25% Submissions: 4 Points: 8

Write a C# function that evaluates mathematical expressions with parentheses and basic operators (+, -, *, /). The function should handle parentheses for operation precedence, multiplication and division (equal precedence), addition and subtraction (equal precedence), proper operator precedence, negative numbers, and spaces in the expression.

Example 1
    

  • Input: s = "3 + 5 * 2"
    • 

  • Output: 13
    • 

  • Explanation: 
      
   
    • Step 1: Parse the expression, identifying numbers and operators.
      • 
   
    • Step 2: Apply operator precedence rules (multiplication before addition).
      • 
   
    • Step 3: Calculate 5 * 2 = 10.
      • 
   
    • Step 4: Calculate 3 + 10 = 13.
      • 
   
    • Step 5: Return the final result 13.
      • 

    •
Example 2
    

  • Input: s = "(4 + 2) * 3 - 6 / 2"
    • 

  • Output: 15
    • 

  • Explanation: 
      
   
    • Step 1: Evaluate the parenthesized expression (4 + 2) = 6.
      • 
   
    • Step 2: Apply multiplication operation: 6 * 3 = 18.
      • 
   
    • Step 3: Apply division operation: 6 / 2 = 3.
      • 
   
    • Step 4: Apply subtraction: 18 - 3 = 15.
      • 
   
    • Step 5: Return the final result 15.
      • 

    •
Constraints
    

  • 1 ≤ s.length ≤ 100
    • 

  • s consists of digits (0-9), '+', '-', '*', '/', '(', ')', and spaces
    • 

  • The expression is valid and can be evaluated to a 32-bit integer
    • 

  • Time Complexity: O(n) where n is the length of the expression
    • 

  • Space Complexity: O(n) for storing intermediate results and operands
    •
NumberStackGoldman SachsSamsung
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Hint
Solution

Solution Hints

    
  
  • Use two stacks: one for numbers and one for operators
    • 
  
  • Process the expression from left to right
    • 
  
  • Handle parentheses by using recursion or stack operations
    • 
  
  • Consider operator precedence when evaluating operations
    • 
  
  • Use a helper function to perform calculations based on operators
    •

Steps to solve by this approach:

 Step 1: Parse the expression from left to right, handling numbers and operators.
 Step 2: Use stacks to manage the order of operations and handle parentheses.
 Step 3: Implement operator precedence (* and / have higher precedence than + and -).
 Step 4: Process opening parentheses by pushing onto stack, and closing parentheses by computing the enclosed expression.
 Step 5: After processing the entire expression, apply any remaining operations in the stack.

Submitted Code :