Difference between revisions of "Fibonacci sequence"
(Decared temp in code solution at beginning of program instead of inline (bad practice)) |
(Fixed typos and formatting problems) |
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|Solution= | |Solution= | ||
− | In order to get | + | In order to get user input from JOptionPane, you will need to import the swing package.<br> |
− | You can import swing package by <br | + | You can import swing package by <br> |
− | <br | + | <br> |
<pre> | <pre> | ||
import javax.swing.*; | import javax.swing.*; | ||
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import javax.swing.JOptionPane; | import javax.swing.JOptionPane; | ||
</pre> | </pre> | ||
− | <br | + | <br> |
− | + | The next step is declaring variables. In this program we will need three inegert variables.<br> | |
− | One variable will be used as F(n) and another variable will be used as F(n-1). <br | + | One variable will be used as F(n) and another variable will be used as F(n-1). <br> |
− | Our initial value for F(n) will be 1 and F(n-1) will be 0, referring to the fibonacci formula. (F(0) = 1, F(1) = 1)<br | + | Our initial value for F(n) will be 1 and F(n-1) will be 0, referring to the fibonacci formula. (F(0) = 1, F(1) = 1)<br> |
− | Once you declare the necessary variables, the last variable will be the casted integer from the user input.<br | + | Once you declare the necessary variables, the last variable will be the casted integer from the user input.<br> |
− | <br | + | <br> |
<pre> | <pre> | ||
int n = 1 | int n = 1 | ||
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int input = cast str to integer | int input = cast str to integer | ||
</pre> | </pre> | ||
− | <br | + | <br> |
− | Once you have all the variables ready, make a for loop that starts from 0 and ends when the counter is less than n (user input).<br | + | Once you have all the variables ready, make a for loop that starts from 0 and ends when the counter is less than n (user input).<br> |
− | In this for loop, the increment will be by 1.<br | + | In this for loop, the increment will be by 1.<br> |
− | <br | + | <br> |
<pre> | <pre> | ||
for(count = 0; count < user input; count increment by 1) | for(count = 0; count < user input; count increment by 1) | ||
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} | } | ||
</pre> | </pre> | ||
− | <br | + | <br> |
− | We will need another variable to keep track of F(n-2). You simply set it F(n-2) = F(n-1) as it starts a new iteration, and set F(n-1) = F(n).<br | + | We will need another variable to keep track of F(n-2). You simply set it F(n-2) = F(n-1) as it starts a new iteration, and set F(n-1) = F(n).<br> |
− | Then sum up the F(n-2) + F(n-1) which will now be F(n).<br | + | Then sum up the F(n-2) + F(n-1) which will now be F(n).<br> |
− | <br | + | <br> |
<pre> | <pre> | ||
(n-2) = (n-1) | (n-2) = (n-1) | ||
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n = (n-2) + (n-1) | n = (n-2) + (n-1) | ||
</pre> | </pre> | ||
− | <br | + | <br> |
− | When the for loop ends, you will have | + | When the for loop ends, you will have the n<sup>th</sup> fibonacci number.<br/> |
At last, print it out using JOptionPane.<br/> | At last, print it out using JOptionPane.<br/> | ||
− | When you are printing the result out with JOptionPane, note that you have to put 'null | + | When you are printing the result out with JOptionPane, note that you have to put 'null' before the actual message you want to print out. <br> |
− | <br | + | <br> |
− | See below for the solution code.<br | + | See below for the solution code.<br> |
}} | }} |
Revision as of 19:22, 8 April 2010
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ProblemWrite a complete Java program titled Fibonacci that:
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Mid-term Review
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SolutionIn order to get user input from JOptionPane, you will need to import the swing package. import javax.swing.*; or import javax.swing.JOptionPane;
int n = 1 int n-1 = 0 String str = get the user input using JOptionPane int input = cast str to integer
for(count = 0; count < user input; count increment by 1) { }
(n-2) = (n-1) (n-1) = n n = (n-2) + (n-1)
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Code |