LeetCode-166 Fraction to recurring Decimal

Given integers representing the numerator and denominator of a fraction, return the fraction in string format.

If the fractional part was 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) ".

Credits:
Special thanks to @Shangrila for adding this problem and creating all test cases.

Test instructions: Converting fractions to decimals

Idea: Using HashMap to deposit already calculated molecules, if a new molecule exists in the map, there is a loop, so use the molecule as the map key. But there was confusion about how the value of map would be determined.

1. Divide the numerator by the integer value of the denominator as value, and then, if a loop occurs, just look at what the value of the loop starts, and find the corresponding position to insert (), but the problem occurs in the 1/90 case;

2. When you see other people's code with different molecules, the corresponding result length as value, this can avoid the problem in 1, so the error value in this way.

Case that might hang:

0/11

1/90;

1/2147483647 (Integer.max_value);

-1/2147483647;

1/-2147483638;

The code is as follows:

 PublicString Fractiontodecimal (intA1,intA2) {        if(A1 = = 0 | | a2 = = 0)return"0"; StringBuilder SB=NewStringBuilder (); Sb.append ((A1>0) ^ (a2>0)? "-":""); LongA = Math.Abs ((Long) A1); Longb = Math.Abs ((Long) A2); Sb.append (Math.Abs (a/b)); A= (a% b) * 10; if(A! = 0) Sb.append ("."); Map<long, integer> map =NewHashmap<long, integer>(); Map.put (NewLong (A1), sb.length ());  while(A! = 0) {Sb.append (a/b);                        Map.put (A, sb.length ()); A= (a% b) * 10; if(Map.containskey (a)) {intpos =Map.get (a); Sb.insert (POS-1, "("); Sb.append (")");  Break; }        }        returnsb.tostring (); }

In the preceding code, the reason for converting the input to a long type is:

1. There is *10 calculation, with an int may overflow;

2. If the integer.min_value is converted to a positive number, the int type will overflow;

LeetCode-166 Fraction to recurring Decimal