在leetcode上刷題的時候,經常需要使用統計元素個數,例如
- words = [“a”,“b”,“c”,“d”,“a”,“c”,“r”]
- 統計列表words中每個元素及其出現的次數
words = ["a","b","c","d","a","c","r"]
from collections import Counter
words_dict_1 = Counter(words)
words_dict_2 = {}
for word in words:
if word not in words_dict_2:
words_dict_2[word] = 1
else:
words_dict_2[word] += 1
words_dict_3 = collections.defaultdict(int)
for word in words:
words_dict_3[word] += 1
words_dict_4 = {}
for word in words:
words_dict_4[word] = words_dict_4.get(word,0) + 1
print(words_dict_1==words_dict_2==words_dict_3==words_dict_4)
print(words_dict_2)