romanToInt function

int romanToInt(String s)

Converts a Roman numeral string to its integer representation.

This function takes a Roman numeral s and returns its integer value.

Time Complexity: O(n), where n is the length of the string s.

Example:

print(romanToInt("MCMXCIV")); // Outputs: 1994

Implementation

int romanToInt(String s) {
  final map = {'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000};
  int result = 0, prev = 0;
  for (int i = s.length - 1; i >= 0; i--) {
    int curr = map[s[i]]!;
    if (curr < prev) {
      result -= curr;
    } else {
      result += curr;
    }
    prev = curr;
  }
  return result;
}