周赛 & 双周赛
参加力扣周赛有10多场了，还没 ak 过，很菜。
有一些知识点感觉还是比较重要的，再次作为笔记方便查看，也分享给大家。
向着 ak 努力！
第 20 场双周赛
- 正确使用
lambda表达式排序。bin(x).count('1')为第一优先级，x为第二优先级。
return sorted(arr,key=lambda x:(bin(x).count('1'),x))
- “子字符串数目”涉及到子串，本题采用双指针滑动窗口的方式。
177 场周赛
from datetime import datetime
class Solution:
def daysBetweenDates(self, date1: str, date2: str) -> int:
date1 = datetime.strptime(date1,'%Y-%m-%d')
date2 = datetime.strptime(date2,'%Y-%m-%d')
res = abs((date1 - date2).days)
return res
关于日期的一些代码模板：
# Credit goes to Websten from forums
#
# Use Dave's suggestions to finish your daysBetweenDates
# procedure. It will need to take into account leap years
# in addition to the correct number of days in each month.
def isLeapYear(year):
"""Given a year returns True if it's a leap year, else False"""
if year % 4 == 0:
if year % 100 == 0:
if year % 400 == 0:
return True
else:
return False
else:
return True
else:
return False
def daysInMonth(year, month):
"""
Given a month, returns the number of days it has.
Takes into consideration leap years.
"""
if isLeapYear(year):
days = [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
else:
days = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
return days[month - 1]
def nextDay(year, month, day):
"""Simple version: assume every month has 30 days"""
if day < daysInMonth(year, month):
return year, month, day + 1
else:
if month == 12:
return year + 1, 1, 1
else:
return year, month + 1, 1
def equal_dates(year1, month1, day1, year2, month2, day2):
""" Checks if two dates are equal or not"""
return year1 == year2 and month1 == month2 and day1 == day2
def dateIsBefore(year1, month1, day1, year2, month2, day2):
"""Returns True if year1-month1-day1 is before
year2-month2-day2. Otherwise, returns False."""
if year1 < year2:
return True
if year1 == year2:
if month1 < month2:
return True
if month1 == month2:
return day1 < day2
return False
def daysBetweenDates(year1, month1, day1, year2, month2, day2):
"""Returns the number of days between year1/month1/day1
and year2/month2/day2. Assumes inputs are valid dates
in Gregorian calendar, and the first date is not after
the second."""
num_days = 0
assert not dateIsBefore(year2, month2, day2, year1, month1, day1)
while not equal_dates(year1, month1, day1, year2, month2, day2):
year1, month1, day1 = nextDay(year1, month1, day1)
num_days += 1
return num_days
def test():
test_cases = [((2012, 1, 1, 2012, 2, 28), 58),
((2012, 1, 1, 2012, 3, 1), 60),
((2011, 6, 30, 2012, 6, 30), 366),
((2011, 1, 1, 2012, 8, 8), 585),
((1900, 1, 1, 1999, 12, 31), 36523)]
for (args, answer) in test_cases:
result = daysBetweenDates(*args)
if result != answer:
print("Test with data:", args, "failed")
else:
print("Test case passed!")
test()
