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599316527/intToRoman.js

Last active August 14, 2019 06:20
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 // Answer to https://leetcode-cn.com/problems/integer-to-roman/ function intToRoman(num) { return [['X', 'V', 'I', 1], ['C', 'L', 'X', 10], ['M', 'D', 'C', 100], ['', '', 'M', 1000]] .reduceRight(function (ret, item, index) { let count = ~~(num / item[3]) % 10; if (!count) return ret; if (count % 5 == 4) return ret + item[2] + item[count > 5 ? 0 : 1]; return ret + item[1].repeat(count >= 5 ? 1 : 0) + item[2].repeat(count % 5); }, ''); };
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 const charValueMapping = { M: 1000, D: 500, C: 100, L: 50, X: 10, V: 5, I: 1 }; function romanToInt(s) { let sum = 0; let len = s.length; for (let i = 0; i < len; i++) { if (i + 1 < len && charValueMapping[s[i]] < charValueMapping[s[i + 1]]) { sum += charValueMapping[s[i + 1]] - charValueMapping[s[i++]]; } else { sum += charValueMapping[s[i]]; } } return sum; };