public class Solution
extends Object
592 - Fraction Addition and Subtraction\.
Medium
Given a string `expression` representing an expression of fraction addition and subtraction, return the calculation result in string format.
The final result should be an [irreducible fraction](https://en.wikipedia.org/wiki/Irreducible_fraction). If your final result is an integer, change it to the format of a fraction that has a denominator `1`. So in this case, `2` should be converted to `2/1`.
**Example 1:**
**Input:** expression = "-1/2+1/2"
**Output:** "0/1"
**Example 2:**
**Input:** expression = "-1/2+1/2+1/3"
**Output:** "1/3"
**Example 3:**
**Input:** expression = "1/3-1/2"
**Output:** "-1/6"
**Constraints:**
* The input string only contains `'0'` to `'9'`, `'/'`, `'+'` and `'-'`. So does the output.
* Each fraction (input and output) has the format `±numerator/denominator`. If the first input fraction or the output is positive, then `'+'` will be omitted.
* The input only contains valid **irreducible fractions** , where the **numerator** and **denominator** of each fraction will always be in the range `[1, 10]`. If the denominator is `1`, it means this fraction is actually an integer in a fraction format defined above.
* The number of given fractions will be in the range `[1, 10]`.
* The numerator and denominator of the **final result** are guaranteed to be valid and in the range of **32-bit** int.