166. Fraction to Recurring Decimal
package LeetCode_166 /** * 166. Fraction to Recurring Decimal * https://leetcode.com/problems/fraction-to-recurring-decimal/description/ * * Given two integers representing the numerator and denominator of a fraction, return the fraction in string format. If the fractional part is repeating, enclose the repeating part in parentheses. Example 1: Input: numerator = 1, denominator = 2 Output: "0.5" Example 2: Input: numerator = 2, denominator = 1 Output: "2" Example 3: Input: numerator = 2, denominator = 3 Output: "0.(6)" * */ class Solution { fun fractionToDecimal(numerator: Int, denominator: Int): String { if (numerator == 0) { return "0" } if (denominator == 0) { return "" } val fractionSb = StringBuilder() //check if need add '-' in first if (numerator < 0 && denominator > 0 || numerator > 0 && denominator < 0) { fractionSb.append("-") } val num = Math.abs(numerator.toLong()) val den = Math.abs(denominator.toLong()) var result = num / den fractionSb.append(result.toString()) //get the remainder var remainder = num % den if (remainder == 0L) { //if divisible return fractionSb.toString() } fractionSb.append(".") //use map to help, key is remainder, value is result length val map = HashMap<Long, Int>() while (remainder != 0L) { val curString = fractionSb.toString() println(map) if (map.containsKey(remainder)) { val begin = map.get(remainder) ?: 0 val part1 = curString.substring(0, begin) val part2 = curString.substring(begin, curString.length) return part1 + "(" + part2 + ")" } map.put(remainder, curString.length) //because we need to get every decimal, so *10 and do again remainder *= 10 result = remainder / den fractionSb.append(result.toString()) //continue to get the new remainder remainder %= den } return fractionSb.toString() } }