问改进该算法的时间复杂度

EN

import numpy as np

def jaccard_similarity(a, b):
    intersection = set(a).intersection(set(b))
    union = set(a).union(set(b))
    return len(intersection)/len(union)

set_1 = [['Pisa','Tower','River','Tuscany'],['London','City','UK','England'],['Berlin','Germany','Munich']]
set_2 = [['Pisa','Arno','River','Tuscany','Florence','London','Tower'],['Germany','German','UBanh'],['London','City','UK','England','Europe']]

pairs = []

for vect_1 in set_1:
    dist = []
    for vect_2 in set_2:
        dist.append(jaccard_similarity(vect_1,vect_2))
    pairs.append(np.argmax(dist))

print(pairs)