166. 分数到小数

题意：

解题思路：

思路：模拟除法过程

PHP代码实现：

class Solution {
    /**
     * @param Integer $numerator
     * @param Integer $denominator
     * @return String
     */
    function fractionToDecimal($numerator, $denominator) {
        if ($denominator == 0) return "0";
        $ans = "";
        if (($numerator < 0 && $denominator > 0) 
            || ($numerator > 0 && $denominator < 0)) {
            $ans = "-";
        }
        $n = abs($numerator);
        $d = abs($denominator);
        $ans .= floor($n / $d);
        $mod = $n % $d;
        if ($mod == 0) return $ans;
        $ans .= ".";
        $map = [];
        while ($mod != 0) {
            if (isset($map[$mod])) {
                $ans = substr_replace($ans, "(", $map[$mod], 0);
                $ans .= ")";
                break;
            }
            $map[$mod] = strlen($ans);
            $mod *= 10;
            $ans .= floor($mod / $d);
            $mod %= $d;
        }
        return $ans;
    }
}

GO代码实现：

func fractionToDecimal(numerator int, denominator int) string {
    if denominator == 0 {return ""}
    var ans string
    if numerator * denominator < 0 {
        ans += "-"
    }
    n, d := ABS(numerator), ABS(denominator)
    ans += strconv.Itoa(n / d)
    mod := n % d
    if mod == 0 {return ans}
    ans += "."
    hm := make(map[int]int)
    rptPos := -1
    for (mod != 0) {
        if pos, ok := hm[mod]; ok {
            rptPos = pos
            break
        }
        hm[mod] = len(ans)
        mod *= 10
        ans += strconv.Itoa(mod / d)
        mod %= d
    }
    if rptPos == -1 {
        return ans
    }
    return fmt.Sprintf("%s(%s)", ans[:rptPos], ans[rptPos:])
}
func ABS(v int ) int {
    if v < 0 {return -v}
    return v
}