How to code this algorithm in PHP?

Question

I have a complex algorithm that I try to code in PHP but it's a bit complicated for a beginner like me. So I need your help guys
I have an array of unknown numbers starting fron t1 up to tn. I don't know its length actually.like

(t1,t2,t3,t4,.....,tn)

And I want to test a condition on the first elemnt if not, on the last element if not will test a common condition against the values from t2 to tn-1
I also have values called s , c & b that I will use in the code.
The first condition is :

if c < s -> Do something
if c >= s and c < (s + (t1 - t2)) -> Do something else
if c >= (s + (t1 - tn)) and c < (s + (t1 + b)) -> Do something else

If non of the previous conditions were matched then I wanna test the values from t2 up to tn-1 in the following way

if c >= (s + (t1 - t2)) and c < (s + (t1 - t3)) -> Do something that's bound to t2 value
if c >= (s + (t1 - t3)) and c < (s + (t1 - t4)) -> Do somehting else

and so on up to tn-1 .. I don't know how many values there are in the array so i need to do this dynamically

Can any one help me ? It will be a great help indeed

Mike · Accepted Answer · 2010-01-31 23:51:11Z

1

Let's imagine for a moment this isn't your homework.

The first condition is boring, it's IF statements with a check to make sure t2 exists and a count() to find tn. Second part is slightly more interesting:

$homework = array(t1,t2....tn);

for (
    $i=2,$n=count($homework),$cs=$c-$s,$cnd_a=$homework[0]-$homework[1];        
    $i<$n;++$i) 
{
    $cnd_b = $homework[0] - $homework[$i];
    if ($cs >= $cnd_a && $cs < $cnd_b) do_no_study($homework[$i-1]);
    $cnd_a = $cnd_b;
}

Or something along those lines.

edited Jan 31, 2010 at 23:51

answered Jan 31, 2010 at 23:39

Mike

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Amirshk · Accepted Answer · 2010-01-31 23:05:27Z

0

This is could be a kick start for you:

<?php

function check_condition($value, $pos)
{
    // do your magic
    return TRUE; // or FALSE;
}

$values = array(1,2,3,4,5,6,7,8,9);

// Array length
$arr_length = length($values);

// Check the first condition
for ($i=0; $i<($arr_length/2); $i++)
{
    if (check_condition($values[$i], $i))
    {   
        echo "condition met at start";
        break;
    }
    if (check_condition($values[$i], $arr_length-$i))
    {
        echo "condition met at start";
        break;
    }
}

?>

answered Jan 31, 2010 at 23:05

Amirshk

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Phil Wallach · Accepted Answer · 2010-01-31 23:20:57Z

0

Try this:

$t = array(); // your array
$len = count($t);

if ($c < $s)
    Do_something();
else if ($c >= $s && $c < ($s + ($t[0] - $t[1])))
    Do_something_else();
else if ($c >= ($s + ($t[0] - $t[$len - 1])) && $c < ($s + ($t[0] + b)))
    Do_something_else_again();
else
    for ($i = 1; $i < $len - 1; $i++)
        if ($c >= ($s + ($[0] - $t[$i])) && $c < ($s + ($t[0] - $t[$i + 1)))
            Do_something_thats_bound_to_value($t, $i);

Note that "$c >= $s" is not needed in the second "if" statement except for clarity.

answered Jan 31, 2010 at 23:20

Phil Wallach

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