PHP - Largest Triple Product solution - php

Question

You're given a list of n integers arr[0..(n-1)]. You must compute a list output[0..(n-1)] such that, for each index i (between 0 and n-1, inclusive), output[i] is equal to the product of the three largest elements out of arr[0..i] (or equal to -1 if i < 2, as arr[0..i] then includes fewer than three elements). Note that the three largest elements used to form any product may have the same values as one another, but they must be at different indices in arr.
Test example:
var arr_2 = [2, 4, 7, 1, 5, 3];
var expected_2 = [-1, -1, 56, 56, 140, 140];
I solved the LPT problem using heaps in PHP. But I'm wondering if there's any way to further optimize this?
I'm creating a min heap of 3 and then pulling the top if it is less than the new element.
function findMaxProductWithHeap($arr): array
{
$out = [];
$product = 1;
$largest = new SplMinHeap();
foreach($arr as $index => $elem)
{
if($index <= 2){
$largest->insert($elem);
$product = $elem*$product;
$out[] = $index < 2 ? -1 : $product;
} else {
if($nums->top() < $elem){
$product = $elem*$product/$nums->top();
$largest->extract();
$largest->insert($elem);
}
$out[] = $product;
}
}
return $out;
}
I also solved this without heaps, just an array of 3 which is sorted on every iteration.
function findMaxProduct($arr) {
$out = [];
$product = 1;
$largest = [];
foreach($arr as $index => $elem)
{
sort($largest);
if($index <= 2){
$largest[] = $elem;
$product = $elem*$product;
$out[] = $index < 2 ? -1 : $product;
} else {
if($largest[0] < $elem){
$product = $elem*$product/$largest[0];
$largest[0] = $elem;
//var_dump($product);
}
$out[] = $product;
}
}
return $out;
}
Thanks.

Answer 1

No conditions, natsort, flexible optional params, works with primitive structures.
function solution($array, $heap_size = 3, $default = -1)
{
$result = [];
while ($array)
{
$heap[] = array_shift($array);
rsort($heap, SORT_NATURAL);
$heap = array_slice($heap, 0, $heap_size);
$result[] = array_product($heap);
}
$replacement = array_fill(0, min(count($result), $heap_size - 1), $default);
return $replacement + $result;
}