Roman to Integer
Hashing, Sorting, and Parsing DSA practice problem on Onlearn.
Difficulty: easy.
Topics: Roman Number to Integer and vice versa, Strings, Map, String Manipulation, Conditional Statements, Loops, Greedy Algorithm, Optimization, edge cases, string processing, greedy algorithm, hash map, number conversion, Roman Numerals, String to Integer (atoi), Hashing & Hash Maps.
Roman Numerals Conversion Roman numerals are represented by seven different symbols: I, V, X, L, C, D 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 ones 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, 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. Given a Roman numeral, convert it to an integer. Task 1: Roman to Integer Given a Roman numeral, convert it to an integer. Input Specification: The input will be a single string s representing a Roman numeral. The input is guaranteed to be a valid Roman numeral in the range [1, 3999]. Output Specification: Return the integer equivalent of the given Roman numeral. 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]. Sample Input 1 (Roman to Integer): Sample Output 1 (Roman to Integer): Sample Input 2 (Roman to Integer): Sample Output 2 (Roman to Integer): Task 2: Integer to Roman Given an integer, convert it to a Roman numeral. Input Specification: The input will be a single integer num. Output Specification: Return the Roman numeral representation of num as a string. Constraints: 1 <= num <= 3999 Sample Input 1 (Integer to Roman): Sample Output 1 (Integer to Roman): Sample Input 2 (Integer to Roman): Sample Output 2 (Integer to Roman):