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Roman to Integer Conversion

Certification: Basic Level Accuracy: 100% Submissions: 4 Points: 5

Write a Java program to convert a Roman numeral to an integer. Roman numerals are represented by combinations of letters from the Latin alphabet: I, V, X, L, C, D, and M.

Example 1
    

  • Input: s = "III"
    • 

  • Output: 3
    • 

  • Explanation:

      

    • Step 1: "III" consists of three I's.
      • 

    • Step 2: I represents 1 in Roman numeral.
      • 

    • Step 3: 1 + 1 + 1 = 3.
      • 

    •
Example 2
    

  • Input: s = "MCMXCIV"
    • 

  • Output: 1994
    • 

  • Explanation:

      

    • Step 1: "MCMXCIV" consists of the following Roman numerals.
      • 

    • Step 2: M = 1000, CM = 900, XC = 90, IV = 4.
      • 

    • Step 3: 1000 + 900 + 90 + 4 = 1994.
      • 

    •
Constraints
    

  • 1 ≤ s.length ≤ 15
    • 

  • s contains only the characters ('I', 'V', 'X', 'L', 'C', 'D', 'M')
    • 

  • It is guaranteed that s is a valid roman numeral in the range [1, 3999]
    • 

  • Time Complexity: O(n)
    • 

  • Space Complexity: O(1)
    •
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Hint
Solution

Solution Hints

    
  
  • Create a mapping of Roman numerals to their corresponding integer values
    • 
  
  • Traverse the string from left to right
    • 
  
  • If the current value is greater than or equal to the next value, add it to the result
    • 
  
  • If the current value is less than the next value, subtract it from the result
    • 
  
  • Return the final result
    •

Steps to solve by this approach:

 Step 1: Create a HashMap to store the mapping of Roman numerals to their corresponding integer values.
 Step 2: Initialize a result variable to 0.
 Step 3: Iterate through the input string from left to right.
 Step 4: For each character, check if it's the last character or its value is greater than or equal to the next character.
 Step 5: If true, add the current character's value to the result; otherwise, subtract it.
 Step 6: Continue until all characters are processed.
 Step 7: Return the final result.

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