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)".
Hint:
No scary math, just apply elementary math knowledge. Still remember how to perform a long division?
Try a long division on 4/9, the repeating part is obvious. Now try 4/333. Do you see a pattern?
Be wary of edge cases! List out as many test cases as you can think of and test your code thoroughly.
Solution:
public class Solution {
public String fractionToDecimal(int numerator, int denominator) {
StringBuilder sb = new StringBuilder();
sb.append(((numerator<0)==(denominator<0)||numerator==0)?"":"-");
long num = Math.abs((long)numerator);
long den = Math.abs((long)denominator);
sb.append(num/den);
long r = num % den;
sb.append(r==0?"":".");
Map<Long,Integer> map = new HashMap<>();
while(!map.containsKey(r)){
if(r==0) return sb.toString();
map.put(r,sb.length());
sb.append(r*10/den);
r = r*10%den;
}
sb.insert(map.get(r),"(");
sb.append(")");
return sb.toString();
}
}