Is Number of Elapsed Seconds Between Two Times easy or hard?

Number of Elapsed Seconds Between Two Times is classified as an Easy problem. The challenge focuses on careful arithmetic conversion rather than advanced algorithms or data structures. Most candidates solve it quickly once they recognize the total-seconds formula.

Number of Elapsed Seconds Between Two Times Python/Java solution

Python and Java solutions typically follow the same arithmetic formula. Parse or extract the hour, minute, and second components, compute total seconds for both timestamps, then subtract the values. Both implementations run in O(1) time and use O(1) extra space.

How to solve Number of Elapsed Seconds Between Two Times in O(1)?

Convert the start time and end time into total seconds from midnight. After conversion, subtract the start value from the end value to get the elapsed seconds. The computation uses constant-time arithmetic operations only.

What is the best approach for Number of Elapsed Seconds Between Two Times?

The best approach converts both timestamps into total seconds and subtracts them. Use the formula hours * 3600 + minutes * 60 + seconds for each time value. This runs in O(1) time and O(1) space because only a fixed number of arithmetic operations are required.

Is Number of Elapsed Seconds Between Two Times asked at Google/Amazon/Meta?

Time conversion and timestamp arithmetic problems appear frequently in screening rounds at companies like Amazon and Meta because they test implementation accuracy and edge-case handling. Variants involving date-time normalization or interval calculations are also common in backend-focused interviews.

What data structure is used in Number of Elapsed Seconds Between Two Times?

The problem does not require advanced data structures. Most solutions use integer variables to store hours, minutes, seconds, and the computed total seconds. Some implementations parse formatted strings into arrays or lists temporarily before conversion.

What is the time complexity of Number of Elapsed Seconds Between Two Times?

The optimal solution runs in O(1) time complexity and O(1) space complexity. The algorithm performs direct arithmetic conversion without iterating through the elapsed interval. A simulation-based solution would take O(diff) time where diff is the number of elapsed seconds.

Description Hints 2 Solution Video 4:29

3986. Number of Elapsed Seconds Between Two Times

Easy82.5% acceptance

You are given two valid times startTime and endTime, each represented as a string in the format "HH:MM:SS".

Return the number of seconds that have elapsed from startTime to endTime.

Example 1:

Input: startTime = "01:00:00", endTime = "01:00:25"

Output: 25

Explanation:

endTime is 25 seconds ahead of startTime.

Example 2:

Input: startTime = "12:34:56", endTime = "13:00:00"

Output: 1504

Explanation:

endTime is 25 minutes and 4 seconds ahead of startTime, which equals 1504 seconds.

Constraints:

startTime.length == 8
endTime.length == 8
startTime and endTime are valid times in the format "HH:MM:SS"
00 <= HH <= 23
00 <= MM <= 59
00 <= SS <= 59
endTime is not earlier than startTime

Topics

Math String

Hints open one at a time

Hint 1

Convert each time into the total number of seconds since 00:00:00.

Hint 2

The answer is the difference between the two converted values.

4:29

Still stuck?Read the written solution, or watch a walkthrough.

Open solution

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1class Solution:
2    def secondsBetweenTimes(self, startTime: str, endTime: str) -> int:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2

Input

"01:00:00"
"01:00:25"

Input

"12:34:56"
"13:00:00"

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