#if !defined(_egcd_H)
# define _egcd_H (1)
/*Computes the coefficients of the smallest positive linear combination of two
integers _a and _b.
These are a solution (u,v) to the equation _a*u+_b*v==gcd(_a,_b).
_a: The first integer of which to compute the extended gcd.
_b: The second integer of which to compute the extended gcd.
_u: Returns the coefficient of _a in the smallest positive linear
combination.
_v: Returns the coefficient _of b in the smallest positive linear
combination.
Return: The non-negative gcd of _a and _b.
If _a and _b are both 0, then 0 is returned, though in reality the
gcd is undefined, as any integer, no matter how large, will divide 0
evenly.
_a*u+_b*v will not be positive in this case.
Note that the solution (u,v) of _a*u+_b*v==gcd(_a,_b) returned is not
unique.
(u+(_b/gcd(_a,_b))*k,v-(_a/gcd(_a,_b))*k) is also a solution for all
k.
The coefficients (u,v) might not be positive.*/
int egcd(int _a,int _b,int *_u,int *_v);
#endif