Roman to Integer LeetCode Programming Solutions | LeetCode Problem Solutions in C++, Java, & Python [💯Correct]

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Hello Programmers/Coders, Today we are going to share solutions to the Programming problems of LeetCode Solutions in C++, Java, & Python. At Each Problem with Successful submission with all Test Cases Passed, you will get a score or marks and LeetCode Coins. And after solving maximum problems, you will be getting stars. This will highlight your profile to the recruiters.

In this post, you will find the solution for the Roman to Integer in C++, Java & Python-LeetCode problem. We are providing the correct and tested solutions to coding problems present on LeetCode. If you are not able to solve any problem, then you can take help from our Blog/website.

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Link for the ProblemRoman to Integer– LeetCode Problem

Roman to Integer – LeetCode Problem

Problem:

Roman numerals are represented by seven different symbols: IVXLCD and M.

Symbol       Value
I             1
V             5
X             10
L             50
C             100
D             500
M             1000

For example, 2 is written as II in Roman numeral, just two one’s added together. 12 is written as XII, which is simply X + II. The number 27 is written as XXVII, which is XX + V + II.

Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IIII. Instead, the number four is written as IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as IX. There are six instances where subtraction is used:

  • I can be placed before V (5) and X (10) to make 4 and 9. 
  • X can be placed before L (50) and C (100) to make 40 and 90. 
  • C can be placed before D (500) and M (1000) to make 400 and 900.

Given a roman numeral, convert it to an integer.

Example 1:

Input: s = "III"
Output: 3
Explanation: III = 3.

Example 2:

Input: s = "LVIII"
Output: 58
Explanation: L = 50, V= 5, III = 3.

Example 3:

Input: s = "MCMXCIV"
Output: 1994
Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.

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].
Roman to Integer– LeetCode Solutions
class Solution {
 public:
  int romanToInt(string s) {
    int ans = 0;
    vector<int> roman(128);

    roman['I'] = 1;
    roman['V'] = 5;
    roman['X'] = 10;
    roman['L'] = 50;
    roman['C'] = 100;
    roman['D'] = 500;
    roman['M'] = 1000;

    for (int i = 0; i + 1 < s.length(); ++i)
      if (roman[s[i]] < roman[s[i + 1]])
        ans -= roman[s[i]];
      else
        ans += roman[s[i]];

    return ans + roman[s.back()];
  }
};
class Solution {
  public int romanToInt(String s) {
    int ans = 0;
    int[] roman = new int[128];

    roman['I'] = 1;
    roman['V'] = 5;
    roman['X'] = 10;
    roman['L'] = 50;
    roman['C'] = 100;
    roman['D'] = 500;
    roman['M'] = 1000;

    for (int i = 0; i + 1 < s.length(); ++i)
      if (roman[s.charAt(i)] < roman[s.charAt(i + 1)])
        ans -= roman[s.charAt(i)];
      else
        ans += roman[s.charAt(i)];

    return ans + roman[s.charAt(s.length() - 1)];
  }
}
class Solution:
  def romanToInt(self, s: str) -> int:
    ans = 0
    roman = {'I': 1, 'V': 5, 'X': 10, 'L': 50,
             'C': 100, 'D': 500, 'M': 1000}

    for a, b in zip(s, s[1:]):
      if roman[a] < roman[b]:
        ans -= roman[a]
      else:
        ans += roman[a]

    return ans + roman[s[-1]]

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