PHP looping failure when array reaches certain size - php

Question

This has been edited a bit, sorry if any comments are out of context.
So, I'm working on the targeting challenge from gild.com. My solution concept is:
1) determine the worth of each target option (as defined by: how many options remain if it is struck)
2) slice the array at that strike point
3) drop any items with a Value lower that the last strike
4) repeat until array is empty
5) return count of strikes
Here's my latest code. I am on shared 1&1 hosting so I don't have direct access to error logs. I had a workaround in place but it's no longer writing to that file (so I'm guessing the error has changed). But when I was getting output, it was always an undefined offset...
UPDATE: now I've been playing around with echoing output from various points to see what's happening, and I found that this prevents a formal error, but it stops echoing after the depth++; loop
<?php
set_time_limit(0);
$targets=array();
$file="http://www.gild.com/coding_test_cases/missile/missile-a.in";
$input=file_get_contents($file);
$input=str_replace("\n\n","\n",$input);
$targets=explode("\n",$input);
if(strlen($targets[count($targets)-1])==0){
array_pop($targets);
}
$rich=array();
$order=array();
while(count($targets)>0){
for($i=0;$i<count($targets);$i++){
$key=$i;
$depth=0;
while($key<count($targets)){
if($targets[$key]>$targets[$i]){
$depth++;
}
$key++;
}
$rich[$i]=$depth;
echo "."; //-----------------------------------I will make it to the screen
}
echo "hi"; //--------------------------------------------------------I will not
$last_strike=$targets[array_pop(array_keys($rich,max($rich)))];
array_push($order,$last_strike);
$targets=array_slice($targets,array_pop(array_keys($rich,max($rich)))+1);
$rich=array();
$c=count($targets);
for($b=0;$b<$c;$b++){
if($targets[$b]<$last_strike){
array_splice($targets,$b,1,true);
$b--;
$c--;
}
}
}
echo count($order)."\n";
?>

Answer 1

Maybe I'm missing something but isn't your entire code snippet equivalent to this?
$rich = range($_GET['lim'] - 1, 0);
echo $rich[0];
As for your actual error, it sounds like a memory allocation problem. Try rethinking your algorithm for this problem.

Answer 2

I think reason that you have 500 error instead of Human-readable error is switched off dislay_errors ini setting.
Try to switch on it or find error message in your Apache error log