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Practice Roman to Integer

Read the task, work through the examples, and check your approach against the constraints. Use the original LeetCode task for coding and submissions.

Easy#13
LeetCode Problem

Roman to Integer

Hash TableMathString

Problem Statement

Convert a valid Roman numeral into its integer value. Symbol values are I=1, V=5, X=10, L=50, C=100, D=500, and M=1000. Usually values are added. The subtractive pairs IV, IX, XL, XC, CD, and CM instead represent 4, 9, 40, 90, 400, and 900. Practice approach: Scan left to right. Subtract a symbol when the following symbol has a larger value; otherwise add it. The input is guaranteed valid, so this covers the allowed subtractive pairs. Runtime is O(n) with constant extra storage.

Source: Roman to Integer on LeetCode. Use the original task for its coding environment and submissions.

Examples

# Example 1

Input
s = "III"
Output
3

# Example 2

Input
s = "LVIII"
Output
58

# Example 3

Input
s = "MCMXCIV"
Output
1994

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].

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← Previous Integer to RomanNext → Longest Common Prefix

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