Question

The happy number can be defined as a number which returns 1 when replaced by the sum of the square of each digit. For instance, 13 is a happy number because 12+32=10→12+02=1 . Number 32 is a happy number because 32+22=13→12+32=10→12+02=1 . Other examples of happy numbers are 7, 28, 100, 320. A number is unhappy if the process yields a 4. Which of the following constructs would we need to find out if a number is happy?(1 point)
Responses

queue
queue

for loop
for loop

while loop
while loop

list

Answer 1

To determine whether a number is a happy number, the best construct to use would be a **while loop**. This is because we need to repeatedly replace the number with the sum of the squares of its digits until we either reach 1 (indicating it is a happy number) or enter a cycle that includes the number 4 (indicating it is unhappy). A while loop is appropriate for this type of repeated checking until a condition is met.

To summarize:

- **While loop**: Yes, this is necessary to continuously apply the transformation until a condition is met (either reaching 1 or falling into the unhappy cycle).
- **For loop**: No, this is not suitable here because the number of iterations isn't predetermined and can vary based on the input number.
- **Queue**: No, a queue isn't necessary for tracking the number transformations in this case.
- **List**: Potentially useful for tracking seen numbers to detect cycles, but primarily a while loop is essential for the core logic.

Thus, the most essential construct for the happy number check is the **while loop**.