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Roman to Integer

Certification: Basic Level Accuracy: 0% Submissions: 0 Points: 5

Write a C program to convert a Roman numeral to an integer. Roman numerals are represented by combinations of letters from the Latin alphabet. Roman numerals are I, V, X, L, C, D, and M which represent the values 1, 5, 10, 50, 100, 500, and 1000 respectively. Roman numerals are usually written largest to smallest from left to right. However, in some cases, a smaller numeral appears before a larger numeral, and in this case, the smaller value is subtracted from the larger value.

Example 1
    
  
  • Input: s = "LVIII"
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  • Output: 58
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  • Explanation: 
    • We break down "LVIII" as "L" + "V" + "III". 
    • L = 50, V = 5, I = 1, I = 1, I = 1. 
    • 50 + 5 + 1 + 1 + 1 = 58. Therefore, the Roman numeral "LVIII" represents the integer 58.
    •
Example 2
    
  
  • Input: s = "MCMXCIV"
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  • Output: 1994
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  • Explanation: 
    • We break down "MCMXCIV" as "M" + "CM" + "XC" + "IV".
    • M = 1000, CM = 900 (1000-100), XC = 90 (100-10), IV = 4 (5-1). 
    • 1000 + 900 + 90 + 4 = 1994. 
    • Therefore, the Roman numeral "MCMXCIV" represents the integer 1994.
    •
Constraints
    
  
  • The input string represents a valid Roman numeral in the range [1, 3999]
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  • The string length will be between 1 and 15
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  • The string will only contain the characters 'I', 'V', 'X', 'L', 'C', 'D', 'M'
    • 
  
  • Time Complexity: O(n), where n is the length of the input string
    • 
  
  • Space Complexity: O(1)
    •
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Hint
Solution

Solution Hints

    
  
  • Create a mapping for each Roman numeral character to its integer value
    • 
  
  • Iterate through the input string from left to right
    • 
  
  • For each character, compare its value with the value of the next character
    • 
  
  • If the current value is less than the next value, subtract it from the result
    • 
  
  • Otherwise, add it to the result
    •

Steps to solve by this approach:

 Step 1: Create a mapping to store the values of each Roman numeral character (I=1, V=5, X=10, L=50, C=100, D=500, M=1000).

 Step 2: Initialize the result to 0.

 Step 3: Iterate through the Roman numeral string from left to right.

 Step 4: For each character, check if its value is less than the value of the next character.

 Step 5: If it is less (like in the case of "IV" where I=1 is less than V=5), subtract the current value from the result.

 Step 6: If it is not less (or if it's the last character), add the current value to the result.

 Step 7: Return the final result after processing all characters.

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