How to break nest loop (bench solutions)

<?php

//Problem: When the investList run up to 10000, the loop times can be 10000*10000=100000000, how to optimize this?

//create test data

$investList = [];

$times = 5000;

for($i = 1; $i <= $times; $i++) {

$investList[] = [

'id' => $i,

'cash' => mt_rand(1, 10000),

];

}

echo 'Run Times: ' . $times, "\n";

//copy a investList as refundList but shuffle it

$refundList = $investList;

shuffle($refundList);

//nest loop solution bench

$refundList1 = $refundList;

bench();

foreach($refundList1 as $index => $refund) {

foreach($investList as $invest) {

if($invest['id'] == $refund['id']) {

$refundList1[$index]['invest_cash'] = $invest['cash'];

}

}

}

echo 'Execute Time(nest loop): ' . bench(), "\n";

//break nest loop solution bench

$refundList2 = $refundList;

bench();

$investList = array_combine(array_column($investList, 'id'), $investList);

foreach($refundList2 as $index => $refund) {

#foreach($investList as $invest) {

#if($invest['id'] == $refund['id']) {

if(isset($investList[$refund['id']])) {

$invest = $investList[$refund['id']];

$refundList2[$index]['invest_cash'] = $invest['cash'];

}

#}

#}

}

echo 'Execute Time(break nest loop): ' . bench(), "\n";

//check two solution's result match in the end

$result = (md5(print_r($refundList1, true)) === md5(print_r($refundList2, true))) ? 'true' : 'false';

echo 'Result Match: ' . $result, "\n";

// print_r($refundList1);

// print_r($refundList2);

//output an item to check its struct

echo 'Last Item: ';

print_r(array_pop($refundList1));

print_r(array_pop($refundList2));

//Solution: https://glot.io/snippets/eggpzzp1tm

/**

* first call bench() store start time

* second call bench() get runtime from last time and reset start time

* @example

bench(); //start

for($i = 0; $i < 1e6; $i++) {

//do something

}

echo 'Execute Time: ' . bench();

*/

function bench() {

static $start;

if (! $start) {

$start = microtime(true);

return;

}

$duration = microtime(true) - $start;

$start = 0;

return $duration;

}