คุณสมบัติของโปรแกรม · ระยะแก้ไขเลเวนชไตน์

def edit_distance(a, b):
    if not isinstance(a, str) or not isinstance(b, str):
        raise ValueError("text.required")
    previous = list(range(len(b) + 1))
    for i, left in enumerate(a, 1):
        current = [i]
        for j, right in enumerate(b, 1):
            current.append(min(current[-1] + 1, previous[j] + 1,
                               previous[j - 1] + (left != right)))
        previous = current
    return previous[-1]