Last updated on January 13th, 2025 at 03:22 am
Here, we see an Integer to Roman LeetCode Solution. This Leetcode problem is solved using different approaches in many programming languages, such as C++, Java, JavaScript, Python, etc.
List of all LeetCode Solution
Topics
Math, String
Companies
Level of Question
Medium
Integer to Roman LeetCode Solution
Table of Contents
1. Problem Statement
Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.SymbolValue 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 an integer, convert it to a roman numeral.
Example 1:
Input: num = 3
Output: “III”
Explanation: 3 is represented as 3 ones.
Example 2:
Input: num = 58
Output: “LVIII”
Explanation: L = 50, V = 5, III = 3.
Example 3:
Input: num = 1994
Output: “MCMXCIV”
Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.
2. Coding Pattern Used in Solution
The provided coding pattern is a “Lookup Table” pattern. This pattern involves precomputing results for specific inputs and storing them in arrays (or dictionaries) for quick access. The code uses arrays (ones, tens, hrns, ths) to store Roman numeral representations for digits in different place values (ones, tens, hundreds, and thousands). The final Roman numeral is constructed by indexing into these arrays based on the input number.
3. Code Implementation in Different Languages
3.1 Integer to Roman C++
class Solution {
public:
string intToRoman(int num) {
string ones[] = {"","I","II","III","IV","V","VI","VII","VIII","IX"};
string tens[] = {"","X","XX","XXX","XL","L","LX","LXX","LXXX","XC"};
string hrns[] = {"","C","CC","CCC","CD","D","DC","DCC","DCCC","CM"};
string ths[]={"","M","MM","MMM"};
return ths[num/1000] + hrns[(num%1000)/100] + tens[(num%100)/10] + ones[num%10];
}
};
3.2 Integer to Roman Java
class Solution {
public String intToRoman(int num) {
String[] ones = {"", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"};
String[] tens = {"", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"};
String[] hrns = {"", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"};
String[] ths = {"", "M", "MM", "MMM"};
return ths[num / 1000] + hrns[(num % 1000) / 100] + tens[(num % 100) / 10] + ones[num % 10];
}
}
3.3 Integer to Roman JavaScript
var intToRoman = function(num) {
const ones = ["", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"];
const tens = ["", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"];
const hrns = ["", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"];
const ths = ["", "M", "MM", "MMM"];
return ths[Math.floor(num / 1000)] + hrns[Math.floor((num % 1000) / 100)] + tens[Math.floor((num % 100) / 10)] + ones[num % 10];
};
3.4 Integer to Roman Python
class Solution:
def intToRoman(self, num):
ones = ["", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"]
tens = ["", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"]
hrns = ["", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"]
ths = ["", "M", "MM", "MMM"]
return ths[num / 1000] + hrns[(num % 1000) / 100] + tens[(num % 100) / 10] + ones[num % 10]
4. Time and Space Complexity
| Time Complexity | Space Complexity | |
| C++ | O(1) | O(1) |
| Java | O(1) | O(1) |
| JavaScript | O(1) | O(1) |
| Python | O(1) | O(1) |