<?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;
}
