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166. 分数到小数

给定两个整数，分别表示分数的分子 numerator 和分母 denominator，以字符串形式返回小数。

如果小数部分为循环小数，则将循环的部分括在括号内。

示例 1:

输入: numerator = 1, denominator = 2
输出: “0.5”
示例 2:

输入: numerator = 2, denominator = 1
输出: “2”
示例 3:

输入: numerator = 2, denominator = 3
输出: “0.(6)”

class Solution {public String fractionToDecimal(int numerator, int denominator) {if (numerator == 0 || denominator == 0) return "0";int sign = 1;if (numerator > 0 && denominator < 0) sign = -1;long big = (long) numerator / (long) denominator;long small = numerator % denominator;StringBuilder result = new StringBuilder(String.valueOf(big));if (sign == -1) result.insert(0, "-");if (small != 0) {result.append(".");StringBuilder smallStr = new StringBuilder();Map<String, Integer> smallIndexs = new HashMap<String, Integer>();while (small != 0) {small *= 10;big = small / denominator;small = small % denominator;String str = small + "_" + big;if (smallIndexs.containsKey(str)) {smallStr.append(")");smallStr.insert(smallIndexs.get(str), "(");break;} else {smallIndexs.put(str, smallStr.length());smallStr.append(Math.abs(big));}}result.append(smallStr);}return result.toString();}
}