def next_perm_string(digits):
    """Generate next Lexographic permutation, digits is string"""
    i = -1
    for i_ in range(1, len(digits)):
        if int(digits[i_-1]) < int(digits[i_]):
            i = i_
    if i == -1:
        return False
    suffix = digits[i:]
    prefix = digits[:i-1]
    pivot = digits[i-1]
    j = 0
    for j_ in range(i, len(digits)):
        if int(digits[j_]) > int(pivot):
            j = j_
    suffix = suffix[:j-i] + pivot + suffix[j-i+1:]
    pivot = digits[j]
    new_digits = prefix + pivot + suffix[::-1]
    return new_digits