What is the algorithm for find the first biggest and second biggest of a list of numbers?

Answer 1

Here's a way to do it in pseudo-code:

• create an array with two elements
• if the first number in the provided list is greater than the second one
  • assign the first one to the first array element
  • assign the second one to the second array element
• else
  • assign the first one to the second array element
  • assign the second one to the first array element
• for every other number in the list
  • if the number is greater than the first element in the array
    • swap their values
  • if the number is greater than the second element in the array
    • assign it to the second element

And that's it. You may notice that this algorithm will work no matter how many of the largest numbers you're looking for. Here's an example of how to do it in PHP:

function getBiggest($values, $quantity){

if(!is_array($values)) return $values;

$highvalues = array();

foreach($values as $value){

for($n = 0; $n < count($highvalues); $n++){

if($value > $highvalues[$n]){

$v = $value;

$value = $highvalues[$n];

$highvalues[$n] = $v;

}

}

if($n < $quantity) $highvalues[$n] = $value;

}

return $highvalues;

}