Given a year year and a month month, return the number of days of that month.
Example 1:
Input: year = 1992, month = 7
Output: 31
Example 2:
Input: year = 2000, month = 2
Output: 29
Example 3:
Input: year = 1900, month = 2
Output: 28
Constraints:
1583 <= year <= 2100
1 <= month <= 12
Solutions
Solution 1: Determine Leap Year
We can first determine whether the given year is a leap year. If the year can be divided by $4$ but not by $100$, or can be divided by $400$, then this year is a leap year.
February has $29$ days in a leap year and $28$ days in a common year.
We can use an array $days$ to store the number of days in each month of the current year, where $days[0]=0$, $days[i]$ represents the number of days in the $i$th month of the current year. Then the answer is $days[month]$.
The time complexity is $O(1)$, and the space complexity is $O(1)$.