# 时间复杂度较高 O(N^2) def numJewelsInStones(J, S): # count = 0 # for i in S: # if i in J: # count+=1 # print(count) return sum([i in J for i in S]) print(numJewelsInStones("aA", "aAAbbbb")) # 预期输出 3 # o(n)的版本 def numJewelsInStones(J, S): stores = {} for c in S: if c in stores: stores[c] = stores[c] + 1 else: stores[c] = 1 count = 0 for c in J: if c in stores: count += stores[c] print(count) J = "aA" S = "aAAbbbb" numJewelsInStones(J, S) J = "z" S = "ZZ" numJewelsInStones(J, S)