Given a positive integer millis, write an asynchronous function that sleeps for millis milliseconds. It can resolve any value.
Note that minor deviation from millis in the actual sleep duration is acceptable.
Example 1:
Input: millis = 100
Output: 100
Explanation: It should return a promise that resolves after 100ms.
let t = Date.now();
sleep(100).then(() => {
console.log(Date.now() - t); // 100
});
Example 2:
Input: millis = 200 Output: 200 Explanation: It should return a promise that resolves after 200ms.
Constraints:
1 <= millis <= 1000When you get asked this question in a real-life environment, it will often be ambiguous (especially at FAANG). Make sure to ask these questions in that case:
The brute force approach to the 'Sleep' problem is like manually testing every possible delay value to see if it works. We try each possible delay, one at a time. We keep trying until we find a delay that causes the program to behave as expected.
Here's how the algorithm would work step-by-step:
def find_sleep_delay_brute_force():
smallestDelayValue = 0
delayIncrement = 0.1
maximumDelayValue = 10
currentDelay = smallestDelayValue
while currentDelay <= maximumDelayValue:
# Simulate running the program with the current delay
programOutput = simulate_program_with_delay(currentDelay)
# Check if the program's output is correct
if is_program_output_correct(programOutput):
return currentDelay
# Increment delay if output is not correct
currentDelay += delayIncrement
#Brute force approach failed, no solution
return None
def simulate_program_with_delay(delay):
# This function should simulate running the program
# with the given delay. For demonstration purposes,
# it returns a string. In a real scenario, this would
# interact with the actual program.
if delay > 5:
return "CorrectOutput"
else:
return "IncorrectOutput"
def is_program_output_correct(output):
# This function checks if the program's output is correct.
# This is a placeholder; a real implementation would
# perform a more thorough check.
return output == "CorrectOutput"
# This is needed to start the brute force algorithm
# with an initial small delay value (zero).
# If a solution is not found within the
# maximum allowed delay, return None.The goal is to pause the program's execution for a specified amount of time. The most efficient way to achieve this is to use the system's built-in functionality designed specifically for pausing execution, avoiding busy-waiting or inefficient looping.
Here's how the algorithm would work step-by-step:
import time
def sleep_function(sleep_duration_seconds):
# Convert duration to seconds.
time_to_sleep = float(sleep_duration_seconds)
# Suspend execution for the specified duration.
time.sleep(time_to_sleep)
def main():
# Get the desired sleep duration from the user.
sleep_duration_input = input("Enter sleep duration in seconds: ")
sleep_duration = float(sleep_duration_input)
print(f"Sleeping for {sleep_duration} seconds...")
sleep_function(sleep_duration)
# Execution resumes here after the sleep duration.
print("Woke up!")
if __name__ == "__main__":
main()| Case | How to Handle |
|---|---|
| Sleep duration is zero. | If the sleep duration is zero, the program should effectively do nothing and return immediately. |
| Sleep duration is negative. | The program should handle this case by either throwing an exception or treating the input as zero, documenting the chosen behavior. |
| Sleep duration is a very large number that could cause an overflow. | The program needs to prevent possible integer overflow by either throwing exception or clamping to an upper limit that the OS supports and documenting this limitation. |
| The system clock is adjusted during sleep. | The program should account for clock changes by comparing the start and end times rather than simply waiting the duration. |
| The program receives a signal during sleep. | The program should catch and handle signals appropriately, potentially interrupting the sleep and returning early. |
| Sleep duration is a floating-point number, and precision is limited. | The program needs to manage floating-point precision to approximate the sleep time as closely as possible using available system calls. |
| The system has limited resources and cannot sleep for the requested duration. | The program should detect and handle potential errors reported by the OS due to resource limitations during the sleep operation and perhaps retry. |
| Sleep interrupted by system events that are not a signal, but a scheduler yielding the process. | The program should ensure that total time elapsed is at least the requested time (by tracking elapsed time and sleeping the remaining time) to fulfill the promise of the function. |