Unidentified Error in Program: Unfriendly Numbers - php

Question

There is a problem in Interview Street challange. Maybe the most easiest of all challenges. "Unfriendly Numbers", is the name and question goes like this.
There is one friendly number and N unfriendly numbers. We want to find how many numbers are there which exactly divide the friendly number, but does not divide any of the unfriendly numbers.
Input Format:
The first line of input contains two numbers N and K seperated by spaces. N is the number of unfriendly numbers, K is the friendly number.
The second line of input contains N space separated unfriendly numbers.
Output Format:
Output the answer in a single line.
I did a PHP programming like this:
<?php
/* Enter your code here. Read input from STDIN. Print output to STDOUT */
$handle = fopen ("php://stdin","r");
$input = fgets($handle);
$num_unfriendly_number=substr($input,0,1);
$friendly_number=substr($input,2,1);
$input2=fgets($handle);
for($i=0;$i<=($num_unfriendly_number); $i=$i+2){
$unfriendly_numbers[$i]=substr($input2,$i,1);
}
//truncates additional input
//now getting divisiors of given friendly numbers
$check_num=1;
//one is always a divisor of any number
$divisior[0]=1;
$arrayindex=1;
for($check_num; $check_num<=$friendly_number; $check_num++){
$hold_var=$friendly_number%$check_num;
if($hold_var==0){
$divisor[$arrayindex]=$check_num;
$arrayindex++;
}
}
$index=0;
foreach($divisor as $test_div){
$output=true;
foreach($unfriendly_numbers as $test_unfrnd){
if($test_unfrnd%$test_div){
$output=false;
}
}
if ($output){
$outputarray[$index]=$test_div;
$index++; //edited afterwards after #Boris's suggestion but didn't work :(
}
}
$num_of_output=count($outputarray);
define('STDOUT',fopen("php://stout","r"));
fwrite(STDOUT,$num_of_output);
?>
The above programme worked fine for 2 testcases but did not applied for other tests. I did some research but did not found any errors. Any helps please. Thanks in advance.

Answer 1

Fist of all I would like to mention that I do not know php. However, I think this is simple enough I can try to help.
Several errors I see:
for($i=0;$i<=($num_unfriendly_number); $i=$i+2){
$unfriendly_numbers[$i]=substr($input2,$i,1);
}
Here you use substr($input2,$i,1);, this however assumes all your unfriendly numbers are digits, which might not always be the case. Better use the split function in php. Replace the whole while with the following:
$unfriendly_numbers = explode(" ", $input2);
After that:
$index=0;
foreach($divisor as $test_div){
$output=true;
foreach($unfriendly_numbers as $test_unfrnd){
if($test_unfrnd%$test_div){
$output=false;
}
}
if ($output){
$outputarray[$index]=$test_div;
}
}
Here you never increase the $index variable. Isn't this meaning that you will override the divisors one with other? USe the operator []=. It appends to an array in php:
if ($output){
$outputarray []= $test_div;
}
EDIT One more error I see is that you count on the friendly number to be a digit too. You can fix this too:
$friendly_number=substr($input,2,1);
->
$friendly_number=explode(" ", $input)[0];

Answer 2

I have the same problem I can't understand why this code can't finish in less than 16 seconds!
I would like to hear your tricks
a = raw_input()# this will read this line: 8 16
b = raw_input()# this will read this line: 2 5 7 4 3 8 3 18
al = a.split()
bl = b.split()
blint = []
fn = int(al[1])
fnlist = [fn]
half_fn = fn / 2 # only I go to half the number to save some time
k = 1
while k <= half_fn:
if fn % k == 0:
fnlist.append(k)
k += 1
plist = []
for j in bl:
blint.append(int(j)) # here I changed the bl list elements which are string to int
for i in fnlist:
for j in blint: #I have the int elements so I don't need every time bring the string and change it to int
if j % i == 0:
plist.append(i)
break
counter = len(fnlist) - len(plist)
print counter