/* * @lc app=leetcode id=13 lang=java * * [13] Roman to Integer * * https://leetcode.com/problems/roman-to-integer/description/ * * algorithms * Easy (51.58%) * Total Accepted: 391.1K * Total Submissions: 752.6K * Testcase Example: '"III"' * * 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, two is written as II in Roman numeral, just two one's added * together. Twelve is written as, XII, which is simply X + II. The number * twenty seven 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. Input is guaranteed to be * within the range from 1 to 3999. * * Example 1: * * * Input: "III" * Output: 3 * * Example 2: * * * Input: "IV" * Output: 4 * * Example 3: * * * Input: "IX" * Output: 9 * * Example 4: * * * Input: "LVIII" * Output: 58 * Explanation: L = 50, V= 5, III = 3. * * * Example 5: * * * Input: "MCMXCIV" * Output: 1994 * Explanation: M = 1000, CM = 900, XC = 90 and IV = 4. * */ class Solution { public int romanToInt(String s) { int sum = 0; int len = s.length(); for (int i = 0; i