What is the time complexity of the Modulo Arithmetic approach?

The time complexity is O(1) because it involves a constant number of arithmetic operations regardless of the input size.

What is the space complexity of the Conditional Logic approach?

The space complexity is O(1) as we only use a single variable to store the total time.

Why do we use modulo 24 in this problem?

We use modulo 24 because the time format cycles every 24 hours. The modulo operator returns the remainder after division, which effectively maps any total hour count back to the 0-23 range.

Calculate Delayed Arrival Time

Difficulty: Easy | Acceptance: 75.50% | Paid: No Topics: Math

You are given a positive integer arrivalTime denoting the arrival time of a train in hours, and an integer delayedTime denoting the amount of delay in hours.

Return the time when the train will arrive at the station.

The time is in 24-hour format (0 to 23).

Examples
Constraints
Modulo Arithmetic
Conditional Logic

Examples

Example 1

Input:

arrivalTime = 15, delayedTime = 5

Output:

Explanation: Arrival time of the train was 15:00 hours. It is delayed by 5 hours. Now it will reach at 15+5 = 20 (20:00 hours).

Example 2

Input:

arrivalTime = 13, delayedTime = 11

Output:

Explanation: Arrival time of the train was 13:00 hours. It is delayed by 11 hours. Now it will reach at 13+11=24 (Which is denoted by 00:00 in 24 hours format so return 0).

Constraints

- 1 <= arrivaltime < 24
- 1 <= delayedTime <= 24

Modulo Arithmetic

Intuition Since the time operates on a 24-hour cycle, we can use the modulo operator to find the remainder after dividing the total time by 24. This effectively handles the wrap-around from 23 to 0.

Steps

Calculate the total time by adding arrivalTime and delayedTime.
Return the total time modulo 24.

python

class Solution:
    def findDelayedArrivalTime(self, arrivalTime: int, delayedTime: int) -&gt; int:
        return (arrivalTime + delayedTime) % 24

Complexity

Time: O(1)
Space: O(1)
Notes: This is the most optimal approach as it uses a single arithmetic operation.

Conditional Logic

Intuition We can manually check if the sum of the arrival time and the delay exceeds a full day (24 hours). If it does, we subtract 24 to get the correct time on the next day.

Steps

Calculate the sum of arrivalTime and delayedTime.
If the sum is less than 24, return the sum.
Otherwise, return the sum minus 24.

python

class Solution:
    def findDelayedArrivalTime(self, arrivalTime: int, delayedTime: int) -&gt; int:
        total = arrivalTime + delayedTime
        return total if total &lt; 24 else total - 24

Complexity

Time: O(1)
Space: O(1)
Notes: Slightly more verbose than the modulo approach but equally efficient for constant time operations.