In mathematics, a [Diophantine equation](https://en.wikipedia.org/wiki/Diophantine_equation) is a polynomial equation, usually with two or more unknowns, such that only the integer solutions are sought or studied.
In this kata we want to find all integers `x, y` (`x >= 0, y >= 0`) solutions of a diophantine equation of the form:
#### x^(2) - 4 \* y^(2) = n
(where the unknowns are `x` and `y`, and `n` is a given positive number)
in decreasing order of the positive xi. 
If there is no solution return `[]` or `"[]" or ""`. (See "RUN SAMPLE TESTS" for examples of returns).
## Examples:
```
solEquaStr(90005) --> "[[45003, 22501], [9003, 4499], [981, 467], [309, 37]]"
solEquaStr(90002) --> "[]"
```
## Hint:
x^(2) - 4 \* y^(2) = (x - 2\*y) \* (x + 2\*y)
import math
def sol_equa(n):
    res = []
    for i in range(1, int(math.sqrt(n)) + 1):
        if n % i == 0:
            j = n // i
            if (i + j) % 2 == 0 and (j - i) % 4 == 0:
                x = (i + j) // 2
                y = (j - i) // 4
                res.append([x, y])
            
    return res

import math
def sol_equa(n):
    res = []
    for i in range(1, int(math.sqrt(n)) + 1):
        if n % i == 0:
            j = n // i
            if (i + j) % 2 == 0 and (j - i) % 4 == 0:
                x = (i + j) // 2
                y = (j - i) // 4
                res.append([x, y])
            
    return res
