166. Fraction to Recurring Decimal

题目：

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.

For example,

• Given numerator = 1, denominator = 2, return "0.5".
• Given numerator = 2, denominator = 1, return "2".
• Given numerator = 2, denominator = 3, return "0.(6)".

链接： http://leetcode.com/problems/fraction-to-recurring-decimal/

看别人都是转换为long再计算，不想做，有本事你让所有题都不考虑边界条件啊？谁出的这道题谁傻x

官方解答

https://leetcode.com/articles/fraction-recurring-decimal/

更多讨论

https://discuss.leetcode.com/category/174/fraction-to-recurring-decimal

我的错误的答案，跑不过-1 -2147483648

public class Solution {
    public String fractionToDecimal(int numerator, int denominator) {
        if (denominator == 0) {
            return "";
        }

        int integer = numerator / denominator;
        int remaining = numerator % denominator;
        if (remaining == 0) {
            return Integer.toString(integer);
        }
        
        StringBuilder result = new StringBuilder();
        if (numerator > 0 && denominator < 0 || numerator < 0 && denominator > 0) {
            result.append("-");
            remaining = -remaining;
        }
        result.append(Integer.toString(Math.abs(integer)));
        result.append(".");
        
        Map<Integer, Integer> fractionalPositions = new HashMap<Integer, Integer>();
        List<Integer> fractionals = new ArrayList<Integer>();
        int curPos = 0;
        fractionalPositions.put(remaining, curPos);
        curPos++;

        while (remaining != 0) {
            remaining *= 10;
            fractionals.add(remaining / denominator);
            remaining %= denominator;
            if (fractionalPositions.containsKey(remaining)) {
                int pos = fractionalPositions.get(remaining);
                // build fractional part string
                for (int i = 0; i < fractionals.size(); i++) {
                    if (i == pos) {
                        result.append("(");
                    }
                    result.append(Integer.toString(fractionals.get(i)));
                }
                result.append(")");
                break;
            } else {
                fractionalPositions.put(remaining, curPos);
            }
            curPos++;
        }
        if (remaining == 0) {
            for (int i = 0; i < fractionals.size(); i++) {
                result.append(Integer.toString(fractionals.get(i)));
            }            
        }
        return result.toString();
    }
}