CONTROL STRUCTURES II: REPETITION - Java Programming: From Problem Analysis to Program Design - page 275

1. Display the input dialog box to prompt the user for the first Fibo-
nacci number—that is, previous1 . Store the string representing
previous1 into inputString .
2. Retrieve the string from inputString , and store the first Fibonacci
number into previous1 .
3. Display the input dialog box to prompt the user for the second
Fibonacci number—that is, previous2 . Store the string represent-
ing previous2 into inputString .
4. Retrieve the string from inputString , and store the second Fibo-
nacci number into previous2 .
5. Create the outputString and append previous1 and previous2 .
6. Display the input dialog box to prompt the user for the desired
Fibonacci number, that is, nthFibonacci . Store the string repre-
senting nthFibonacci into inputString .
7. Retrieve the string from inputString , and store the desired nth
Fibonacci number into nthFibonacci .

MAIN
ALGORITHM

5

8. a.

if (nthFibonacci == 1)

the desired Fibonacci number is the first Fibonacci number.
Copy the value of previous1 into current .

b.

else if (nthFibonacci == 2)

the desired Fibonacci number is the second Fibonacci number.
Copy the value of previous2 into current .

c.

else calculate the desired Fibonacci number as follows:
Since you already know the first two Fibonacci numbers of the
sequence, start by determining the third Fibonacci number.
i. Initialize counter to 3 , to keep track of the calculated
Fibonacci numbers.
ii. Calculate the next Fibonacci number, as follows:

current = previous2 + previous1;

iii. Assign the value of previous2 to previous1 .
iv. Assign the value of current to previous2 .
v. Increment counter .

Repeat Steps 8c(ii)

through 8c(v) until the Fibonacci

number you want is calculated.
The following while loop executes Steps 8c(ii) through
8c(v) and determines the nth Fibonacci number: