我正在用 Python 練習生日悖論問題。我已經運行了很多次，改變了生日的亂數和**回圈運行數**，但概率是 0 或 100%，我無法獲得其他概率，如 50% 等。可以有人幫我查看我的代碼，看看我做錯了什么？非常感謝！！
from random import randint
from datetime import datetime, timedelta
first_day_of_year = datetime(2017, 1, 1)
num_of_ppl = 45
birthdays = []
# get 45 random birthdays list
for i in range(num_of_ppl):
new_birthday = first_day_of_year timedelta(days = randint(0, 365))
birthdays.append(new_birthday)
# find if there's matched birthdays, run 10000 times
dups = 0
duplicates = set()
for i in range(10000):
for bday in birthdays:
if birthdays.count(bday) > 1:
duplicates.add(bday)
if len(duplicates) >= 1:
dups = 1
# calculate the probability
probability = dups/10000 * 100
print(probability)
uj5u.com熱心網友回復：
如果您每次都生成生日串列，則概率與預期一致。此外，我沒有看到需要使用datetime或set物件，我只是用ints 和bools 替換了它們，而沒有在功能上改變任何東西。此外，您可以使用串列推導來在一行中生成生日串列：
from random import randint
num_iterations = 10000
num_people = 45
num_duplicates_overall = 0
# generate a random birthday for each person, check if there was a duplicate,
# and repeat num_iterations times
for i in range(num_iterations):
# start with a new, empty list every time.
# get a list of random birthdays, of length num_people.
birthdays = [randint(0, 365) for _ in range(num_people)]
# Keep track of whether or not there was a duplicate for this iteration
was_duplicate = False
for bday in birthdays:
if birthdays.count(bday) > 1:
# We found a duplicate for this iteration, so we can stop checking
was_duplicate = True
break
if was_duplicate:
num_duplicates_overall = 1
probability = num_duplicates_overall / num_iterations
print(f"Probability: {probability * 100}%")
num_iterations = 1000000使用和輸出num_people = 23：
Probability: 50.6452%
編輯：或者，有這種方法可以檢查重復項，據說速度更快（但主要是我喜歡它，因為它在一行上）：
if len(birthdays) != len(set(birthdays)):
num_duplicates_overall = 1
因此，您的代碼可能看起來像這樣簡單：
from random import randint
num_iterations = 10000
num_people = 45
num_duplicates_overall = 0
for i in range(num_iterations):
birthdays = [randint(0, 365) for _ in range(num_people)]
if len(birthdays) != len(set(birthdays)):
num_duplicates_overall = 1
probability = num_duplicates_overall / num_iterations
print(f"Probability: {probability * 100}%")
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標籤：Python 约会时间 for循环 嵌套循环 生日悖论