Is Day of the Year easy or hard?

Day of the Year is classified as an Easy problem. The main concepts are string parsing, simple arithmetic, and applying the leap year rule correctly.

How to solve Day of the Year in O(1)?

Extract the year, month, and day from the YYYY-MM-DD string. Use a fixed array of month lengths, adjust February to 29 if the year is a leap year, sum the days of months before the given month, and add the day value. Since the loop iterates over at most 12 months, the runtime is constant.

What is the best approach for Day of the Year?

The predefined days-per-month approach is the most common solution. Parse the date, sum the days from previous months, adjust February for leap years, and add the current day. This runs in O(1) time and O(1) space because the number of months is fixed.

What data structure is used in Day of the Year?

Most solutions use a small array (or list) storing the number of days in each month. The algorithm also relies on basic string parsing and conditional logic for leap year detection.

What is the time complexity of Day of the Year?

The standard solution runs in O(1) time and O(1) space. At most 12 months are processed when summing days, which is a constant bound independent of input size.

Day of the Year Python or Java solution approach?

In Python or Java, split the date string to extract year, month, and day, store month lengths in an array, adjust February for leap years, and sum previous months. The implementation is short and runs in constant time.

Is Day of the Year asked at Google, Amazon, or Meta?

Problems involving date parsing, leap year rules, and simple calendar calculations appear in coding interviews across companies like Amazon and Google. While this exact question may not always appear, similar math and string manipulation problems are common.

Description Hints 1 Solution Video 7:09

1154. Day of the Year

Easy50.3% acceptance3 companies

Given a string date representing a Gregorian calendar date formatted as YYYY-MM-DD, return the day number of the year.

Example 1:

Input: date = "2019-01-09"
Output: 9
Explanation: Given date is the 9th day of the year in 2019.

Example 2:

Input: date = "2019-02-10"
Output: 41

Constraints:

date.length == 10
date[4] == date[7] == '-', and all other date[i]'s are digits
date represents a calendar date between Jan 1^st, 1900 and Dec 31^st, 2019.

Asked at 3 companies

Zscaler

Google Meta

Topics

Math String

Hints open one at a time

Hint 1

Have a integer array of how many days there are per month. February gets one extra day if its a leap year. Then, we can manually count the ordinal as day + (number of days in months before this one).

7:09

Still stuck?Read 3 approaches, or watch a walkthrough.

Open solution

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1class Solution:
2    def dayOfYear(self, date: str) -> int:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2

Input

"2019-01-09"

Input

"2019-02-10"

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