How to minimize number of loops?

<?php

$s = "2, 5, 7, 4"; //suppose its an array comes from mySql database (never come duplicate value)

$a = explode(", ", $s);

echo sizeof($a); // 4 will be printed

for ($i=0; $i<100; $i++) {
for ($j=0; $j<sizeof($a); $j++) {
if ($i==$a[$j]) {
echo "<br>$i = MATCH";
}
}
}

?>

output:
4
2 = MATCH
4 = MATCH
5 = MATCH
7 = MATCH

The above for loop will run 500 times in total (main loop=100 & sub loop=400 times).

But is there any way to minimize the loop number and keep the output same?

Actually I want to compare a group of values (300 items) with another group of values (50 items).
If I use my script then the loop will run around 15,300 times. But I want to minimize it.

Note: It is better, if $i matched with any $a[$j] then it will not checkek next $a[$j]

PLEASE HELP

 

Can you post your mysql_query

Otherwise add a limit to the query

LIMIT 0,300

Code (markup):

Example:

("SELECT something FROM table LIMIT 0,300");

Code (markup):

Will return 300 results, starting from 0

 

I agree, you'd rather optimize your SQL query.

 

A better idea would be to have those 2 groups sorted and then you check everything in a single loop, with the help of less-than comparisons, like this:

$i=0;
$j=0;

while (($i < 100) && ($j < sizeof($a)))
{
if ($i == $a[$j])
{
echo "Match ...";
$i++;
$j++;
}
else if ($i < $a[$j])
{
$i++;
}
else if ($i > $a[$j])
{
$j++;
}
}

 

Actually I have 2 table

Table-1
field-name-a -------------(6 or more rows)
------------
4
3
2
7
5
12

Table-2
field-name-b --------------(only 1 row)
------------
2, 5, 7, 4

SO, what will be the query to print the following output?

4 = MATCH
3 = NOT MATCH
2 = MATCH
7 = MATCH
5 = MATCH
12= NOT MATCH

 

You can select the row you need from table A, and put it into an array, and the select the only row from table B, and put it into an array too.
Then, you should sort both of them and then do the check as I mentioned above.

For example, let's say you have the data in the arrays a and b.

Then you sort them, and you check for matches:

//----------------------------------------
// sort a
for ($i=0; $i<sizeof($a); $i++)
{
  $min = $i;  
  for ($j=$i+1; $j<sizeof($a); $j++)
  {
      if ($a[$min] > $a[$j]) $min = $j;
  }

  $aux = $a[$min];
  $a[$min] = $a[$i];
  $a[$i] = $aux;
}
//----------------------------------------
// sort b
for ($i=0; $i<sizeof($b); $i++)
{
  $min = $i;  
  for ($j=$i+1; $j<sizeof($b); $j++)
  {
      if ($b[$min] > $b[$j]) $min = $j;
  }

  $aux = $b[$min];
  $b[$min] = $b[$i];
  $b[$i] = $aux;
}
//----------------------------------------
// check for matches
$i=0;
$j=0;

while (($i < sizeof($a)) && ($j < sizeof($b)))
{
  if ($a[$i] == $b[$j])
  {
    echo "Match ...";
    $i++;
    $j++;
  }
  else if ($a[$i] < $b[$j])
  {
     $i++;
  }
  else if ($a[$i] > $b[$j])
  {
     $j++;
  }
} 

PHP:

 

Sure, if you want it to be efficient, you should use another method for sorting, not the one I used above. Or you can use the php function sort().