# 原始列表
nums = [5, 12, 7, 9, 21, 7, 14]
# 统计数字7出现的次数
count_seven = nums.count(7)
print("数字7出现的次数:", count_seven)
# 判断99是否存在,不存在则添加
if 99 not in nums:
nums.append(99)
print("添加99后的列表:", nums)# your code goes here
IyDljp/lp4vliJfooagKbnVtcyA9IFs1LCAxMiwgNywgOSwgMjEsIDcsIDE0XQojIOe7n+iuoeaVsOWtlzflh7rnjrDnmoTmrKHmlbAKY291bnRfc2V2ZW4gPSBudW1zLmNvdW50KDcpCnByaW50KCLmlbDlrZc35Ye6546w55qE5qyh5pWw77yaIiwgY291bnRfc2V2ZW4pCiMg5Yik5patOTnmmK/lkKblrZjlnKjvvIzkuI3lrZjlnKjliJnmt7vliqAKaWYgOTkgbm90IGluIG51bXM6CiAgICBudW1zLmFwcGVuZCg5OSkKcHJpbnQoIua3u+WKoDk55ZCO55qE5YiX6KGo77yaIiwgbnVtcykjIHlvdXIgY29kZSBnb2VzIGhlcmU=
IyDljp/lp4vliJfooagKbnVtcyA9IFs1LCAxMiwgNywgOSwgMjEsIDcsIDE0XQojIOe7n+iuoeaVsOWtlzflh7rnjrDnmoTmrKHmlbAKY291bnRfc2V2ZW4gPSBudW1zLmNvdW50KDcpCnByaW50KCZxdW90O+aVsOWtlzflh7rnjrDnmoTmrKHmlbDvvJomcXVvdDssIGNvdW50X3NldmVuKQojIOWIpOaWrTk55piv5ZCm5a2Y5Zyo77yM5LiN5a2Y5Zyo5YiZ5re75YqgCmlmIDk5IG5vdCBpbiBudW1zOgogICAgbnVtcy5hcHBlbmQoOTkpCnByaW50KCZxdW90O+a3u+WKoDk55ZCO55qE5YiX6KGo77yaJnF1b3Q7LCBudW1zKQ==
# 原始列表
nums = [5, 12, 7, 9, 21, 7, 14]
# 统计数字7出现的次数
count_seven = nums.count(7)
print("数字7出现的次数:", count_seven)
# 判断99是否存在,不存在则添加
if 99 not in nums:
nums.append(99)
print("添加99后的列表:", nums)