我怎样才能在php中实现FibonacciSecret

Question

I'm trying to get all the characters in that message at positions that are present in the Fibonacci sequence (a sequence formed by the the Fibonacci number sorted in ascending order). Please ignore whitespace characters and use the extended Fibonacci.

Return the obtained characters capitalized and connected by the '-' character.

Example

For message = "The Da Vinci Code is a 2003 mystery-detective novel by Dan Brown",

the output should be

FibonacciSecret(message) = "T-H-H-E-D-V-C-E-M-T".

The first Fibonacci is 0 then the first letter is T

The second Fibonacci is 1 then the second letter is H

The third Fibonacci is 1 then the third letter is H ... and so on.

Thus, the answer should be "T-H-H-E-D-V-C-E-M-T".

Tried Code

<?php
$message = 'The Da Vinci Code is a 2003 mystery-detective novel by Dan Brown';
$str_split = str_split($message);

$x = 0;    
$y = 1;

for($i=0;$i<=10;$i++)    
{    
    $z = $x + $y;    
    $farray[] = $z;     
    $x=$y;       
    $y=$z;     
}  

foreach($farray as $key=>$fvalue){
       echo $str_split[$fvalue]."-";
}

?>

Output

h-T-
E_NOTICE : type 8 -- Undefined offset: -1 -- at line 18
-
E_NOTICE : type 8 -- Undefined offset: -1 -- at line 18
-T-h-h-T-
E_NOTICE : type 8 -- Undefined offset: -1 -- at line 18
-
E_NOTICE : type 8 -- Undefined offset: -1 -- at line 18
-T-

Expected Output

the answer should be "T-H-H-E-D-V-C-E-M-T".

Can anyone tell me. Where im going wrong in this one ?

Answer 1

Your Fibonacci series generation code was not correct, Try this:

Update:

This code will stop once it sum goes out of the range of message length.

$message = 'The Da Vinci Code is a 2003 mystery-detective novel by Dan Brown';

// remove all the spaces from message
$message = str_replace(' ', '', $message);
$str_split = str_split($message);

$x = 0;    
$y = 1;
$next = 0;

//stopping the loop if the character index goes out of range
for($i=1;$next<=count($str_split);$i++)  
{      
    if($i == 1) //for first element use 0 as the sum
    {
        $farray[] = $x; 
        continue;
    }
if($i == 2) //for second element use 1 as the sum
{
     $farray[] = $y; 
    continue;
}

$next = $x + $y;
$x=$y;
$y=$next;

$farray[] = $next; 
}  

foreach($farray as $key=>$fvalue){
   echo $str_split[$fvalue]."--";
}

Original Answer:-

It Works:-

$message = 'The Da Vinci Code is a 2003 mystery-detective novel by Dan Brown';

// remove all the spaces from message
$message = str_replace(' ', '', $message);
$str_split = str_split($message);

$x = 0;    
$y = 1;
$next = 0;

for($i=1;$i<=10;$i++)    
{      
    if($i == 1) //for first element use 0 as the sum
    {
        $farray[] = $x; 
        continue;
    }

    if($i == 2) //for second element use 1 as the sum
    {
         $farray[] = $y; 
        continue;
    }

    $next = $x + $y;
    $x=$y;
    $y=$next;

    $farray[] = $next; 
}  

foreach($farray as $key=>$fvalue){
   echo $str_split[$fvalue]."--";
}