viterbi algorithm

def viterbi(n):
    S_(n-1),P_(n-1) = viterbi(n-1)
    max_p=0
    for s_i,p_i->j in StatusMatrix[S_(n-1)]:
        p = p_i->j * P_(n-1)
        if p>max_p :
            max_p=p
            S_n=s_i
    return S_n,max_p