# Simple 2-liner (and more)

• ``````def solve_equation(equation)
a, x = eval('i = 1i;' + equation.gsub('x', 'i').sub('=', '-(') + ')').rect
"x=#{-a/x}" rescue a != 0 ? 'No solution' : 'Infinite solutions'
end
``````

It's easy to change an equation like `2+3x=5x-7` to an expression for a complex number like `2+3i-(5i-7)`. Then I let Ruby evaluate that and it gives me the total of "x numbers" and the total of "non-x numbers" as the imaginary and real part of the complex number.

Same in Python:

``````def solveEquation(self, equation):
z = eval(equation.replace('x', 'j').replace('=', '-(') + ')', {'j': 1j})
a, x = z.real, -z.imag
return 'x=%d' % (a / x) if x else 'No solution' if a else 'Infinite solutions'
``````

And here's a completely different one using a regular expression to parse the tokens:

``````def solveEquation(self, equation):
x = a = 0
side = 1
for eq, sign, num, isx in re.findall('(=)|([-+]?)(\d*)(x?)', equation):
if eq:
side = -1
elif isx:
x += side * int(sign + '1') * int(num or 1)
elif num:
a -= side * int(sign + num)
return 'x=%d' % (a / x) if x else 'No solution' if a else 'Infinite solutions'``````

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