Is Next Day easy or hard?

Next Day is classified as an Easy problem. The challenge mainly comes from handling edge cases such as February in leap years and transitions like the end of a month or year.

Next Day Python/Java solution

In Python or Java, the problem can be solved either with built-in date libraries or with manual simulation. The manual approach parses the date string, checks leap years, updates day and month boundaries, and formats the output back to YYYY-MM-DD in O(1) time.

How to solve Next Day in O(1)?

Parse the date components, increment the day, and compare it with the maximum days in the current month. If the day exceeds the limit, reset it to 1 and increment the month; if the month exceeds 12, reset it to 1 and increment the year. Leap year rules adjust February to 29 days when needed.

What is the best approach for Next Day?

Manual calendar simulation is the most common approach. Parse the year, month, and day, increment the day, and adjust for month length and leap years. The algorithm runs in O(1) time and O(1) space because it only performs fixed arithmetic checks and formatting.

Is Next Day asked at Google/Amazon/Meta?

Date manipulation problems appear frequently in interviews across large tech companies because they test edge case handling and careful logic. Variants involving leap years, date differences, or calendar simulations are commonly used in screening rounds.

What data structure is used in Next Day?

Most implementations use a small array storing the number of days in each month. Combined with integer variables for year, month, and day, this allows constant-time checks and updates during the simulation.

What is the time complexity of Next Day?

The time complexity is O(1). The algorithm performs a constant number of operations: parsing the date, checking leap year conditions, updating day/month/year values, and formatting the result string.

2758. Next Day - Practice Online

Write code that enhances all date objects such that you can call the date.nextDay() method on any date object and it will return the next day in the format YYYY-MM-DD as a string.

Example 1:

Input: date = "2014-06-20"
Output: "2014-06-21"
Explanation: 
const date = new Date("2014-06-20");
date.nextDay(); // "2014-06-21"

Example 2:

Input: date = "2017-10-31"
Output: "2017-11-01"
Explanation: The day after 2017-10-31 is 2017-11-01.

Constraints:

new Date(date) is a valid date object