Extended Euclidean algorithm
ph
python code is as follows,
def exteuclid(m, n, s0=1, s1=0, t0=0, t1=1):
# s0 := s_{i-1}
# s1 := s_i
# t0 := t_{i-1}
# t1 := t_i
assert m>=n
q = m/n
r = m%n
s = s0 - q*s1
t = t0 - q*t1
if r==0:
return n, s1, t1
else:
return exteuclid(n, r, s1, s, t1, t)
#test
#print exteuclid(240, 46)
#(2, -9, 47)