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Fraction2Decimal.java
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Fraction2Decimal.java
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package Leetcode;
import java.util.HashMap;
import java.util.Map;
/**
* 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.
*
* If multiple answers are possible, return any of them.
*
*
*
* 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)"
*
* Example 4:
*
* Input: numerator = 4, denominator = 333
* Output: "0.(012)"
*
* Example 5:
*
* Input: numerator = 1, denominator = 5
* Output: "0.2"
*
*
*
* Constraints:
*
* -231 <= numerator, denominator <= 231 - 1
* denominator != 0
*/
public class Fraction2Decimal {
public static String fractionToDecimal(int numerator, int denominator) {
if (numerator == 0)
return "0";
String sign = ((numerator > 0) ^ (denominator > 0)) ? "-" : "";
long num = Math.abs((long)numerator);
long den = Math.abs((long)denominator);
return sign + (num / den) + computeDecimal(num % den, den);
}
private static String computeDecimal(long numerator, long denominator) {
if(numerator == 0)
return "";
StringBuilder result = new StringBuilder();
result.append(".");
Map<Long, Integer> numberIndex = new HashMap<>();
numberIndex.put(numerator, result.length());
while (numerator != 0) {
numerator *= 10;
result.append(numerator / denominator);
numerator %= denominator;
// If the same numerator is observed before
// Add the brackets to index where that numerator was observed
if (numberIndex.containsKey(numerator)) {
int index = numberIndex.get(numerator);
result.insert(index, "(");
result.append(")");
break;
}
numberIndex.put(numerator, result.length());
}
return result.toString();
}
public static void main(String[] args) {
System.out.println(fractionToDecimal(1, 2));
System.out.println(fractionToDecimal(2,3));
}
}