def is_answer(seq):
    """Found an answer if:"""
    return all(seq.count(i)==seq[i] for i in range(10))

def reset(last):
    seq = [0]*10
    seq[0] = 9
    seq[last] = 1
    return seq

def next_candidate(seq):
    if seq[0] != 0:
        seq[0] -= 1
        seq[1] += 1
        if seq[1] > 9:
            return reset(2)
        return seq
    # seq[0] == 0
    # Find first non-zero value. Add 1 to following value and
    # move remainder back down to 0
    for first in range(10):
        if seq[first] != 0:
            break
    seq[first+1] += 1
    seq[0] = seq[first]-1
    seq[first] = 0
    return seq

def scan():
    seq = reset(1)
    trials = 1
    while not is_answer(seq):
        trials += 1
        seq = next_candidate(seq)

    print("Found {} after {} trials".format(''.join(str(c) for c in seq), trials))

if __name__=='__main__':
    scan()