Get nearest sequence result from an array and given pattern with PHP - php

Question

I am trying to get year and month from the letters using established sequence. I know that the sequence is based on the following letters:
$letters = array('B','C','D','F','G','H','J','K','L','M','N','P','R','S','T','V','W','X','Y','Z');
It started with 0000BBB and when it reaches 9999 it becomes BBC, BBD etc. So I don't need the numbers in that case and only letters as I have a list of last registered sequence per year and month like this:
$plates = array(
array('2018','KHF','KHX','KJV','KKN','KLM','KML','KNK','KPD','KPR','KPT','----','----'),
array('2017','JWN','JXF','JYB','JYT','JZP','KBM','KCH','KCV','KDK','KFB','KFV','KGN'),
array('2016','JLN','JMF','JMY','JNR','JPK','JRG','JRZ','JSL','JTB','JTR','JVH','JVZ'),
array('2015','JCK','JCY','JDR','JFG','JFW','JGP','JHJ','JHT','JJH','JJW','JKK','JKZ'),
array('2014','HVN','HVZ','HWM','HXB','HXN','HYD','HTY','HZB','HZL','HZZ','JBL','JBY'),
array('2013','HNT','HPC','HPN','HPY','HRK','HRX','HSK','HSR','HSZ','HTK','HTV','HVF'),
array('2012','HJC','HJM','HKB','HKL','HKX','HLK','HLW','HMD','HML','HMT','HNC','HNK'),
array('2011','HBP','HCB','HCR','HDC','HDR','HFF','HFT','HGC','HGM','HGX','HHH','HHT'),
array('2010','GTC','GTS','GVM','GWC','GWV','GXP','GYD','GYM','GYX','GZJ','GZT','HBG'),
array('2009','GKS','GLC','GLP','GMC','GMN','GNF','GNY','GPJ','GPW','GRM','GSC','GSR'),
array('2008','FZR','GBN','GCK','GDH','GFC','GFY','GGV','GHG','GHT','GJJ','GJV','GKH'),
array('2007','FKY','FLV','FNB','FNZ','FRC','FSJ','FTP','FVJ','FWC','FXB','FXY','FYY'),
array('2006','DVW','DWT','DXZ','DYY','FBC','FCJ','FDP','FFK','FGF','FHD','FJD','FKC'),
array('2005','DFZ','DGX','DHZ','DKB','DLD','DMJ','DNP','DPK','DRG','DSC','DTB','DVB'),
array('2004','CRV','CSS','CTT','CVR','CWR','CXT','CYY','CZP','DBJ','DCH','DDG','DFF'),
array('2003','CDV','CFM','CGJ','CHF','CJC','CKB','CLD','CLV','CMM','CNK','CPF','CRC'),
array('2002','BSL','BTF','BTZ','BVW','BWT','BXP','BYP','BZF','BZV','CBP','CCH','CDC'),
array('2001','BFJ','BGF','BHG','BJC','BKB','BLC','BMF','BMW','BNL','BPG','BRB','BRT'),
array('2000','---','---','---','---','---','---','---','---','BBJ','BCD','BCY','BDR')
);
That means that array index 0 is the year and from 1 to 12 would be month. I am trying to find a match but then realize I can not search exact value and need to look for nearest value based on letters.
I would deeply appreciate if anyone could direct me in right direction what would be the best method of doing this.
This is a test so far but this will just return an exact match, I would have to search any possible letters such as KHW as an example that would have to match as nearest value to KHX
foreach ($plates as $key => $val) {
$search = array_search('KHX', $plates[$key]);
if($search){
echo $search."\n";
echo $plates[$key][0];
break;
}
}

Answer 1

You can solve it with O(log n) with a binary search. But in a more straightforward solution, you can solve it with O(n).
You can calculate the difference between each word with the below algorithm.
‍‍
<?php
function strToInt($str)
{
$result = 0;
for ($i = 0; $i < strlen($str); $i++) {
$result = $result * 100 + ord($str[$i]);
}
return $result;
}
function find($searchStr)
{
$plates = [
['2018','KHF','KHX','KJV','KKN','KLM','KML','KNK','KPD','KPR','KPT','----','----'],
['2017','JWN','JXF','JYB','JYT','JZP','KBM','KCH','KCV','KDK','KFB','KFV','KGN'],
['2016','JLN','JMF','JMY','JNR','JPK','JRG','JRZ','JSL','JTB','JTR','JVH','JVZ'],
['2015','JCK','JCY','JDR','JFG','JFW','JGP','JHJ','JHT','JJH','JJW','JKK','JKZ'],
['2014','HVN','HVZ','HWM','HXB','HXN','HYD','HTY','HZB','HZL','HZZ','JBL','JBY'],
['2013','HNT','HPC','HPN','HPY','HRK','HRX','HSK','HSR','HSZ','HTK','HTV','HVF'],
['2012','HJC','HJM','HKB','HKL','HKX','HLK','HLW','HMD','HML','HMT','HNC','HNK'],
['2011','HBP','HCB','HCR','HDC','HDR','HFF','HFT','HGC','HGM','HGX','HHH','HHT'],
['2010','GTC','GTS','GVM','GWC','GWV','GXP','GYD','GYM','GYX','GZJ','GZT','HBG'],
['2009','GKS','GLC','GLP','GMC','GMN','GNF','GNY','GPJ','GPW','GRM','GSC','GSR'],
['2008','FZR','GBN','GCK','GDH','GFC','GFY','GGV','GHG','GHT','GJJ','GJV','GKH'],
['2007','FKY','FLV','FNB','FNZ','FRC','FSJ','FTP','FVJ','FWC','FXB','FXY','FYY'],
['2006','DVW','DWT','DXZ','DYY','FBC','FCJ','FDP','FFK','FGF','FHD','FJD','FKC'],
['2005','DFZ','DGX','DHZ','DKB','DLD','DMJ','DNP','DPK','DRG','DSC','DTB','DVB'],
['2004','CRV','CSS','CTT','CVR','CWR','CXT','CYY','CZP','DBJ','DCH','DDG','DFF'],
['2003','CDV','CFM','CGJ','CHF','CJC','CKB','CLD','CLV','CMM','CNK','CPF','CRC'],
['2002','BSL','BTF','BTZ','BVW','BWT','BXP','BYP','BZF','BZV','CBP','CCH','CDC'],
['2001','BFJ','BGF','BHG','BJC','BKB','BLC','BMF','BMW','BNL','BPG','BRB','BRT'],
['2000','---','---','---','---','---','---','---','---','BBJ','BCD','BCY','BDR']
];
$minYear = null;
$minKey = null;
$minDiff = strToInt('ZZZ');
$searchInt = strToInt($searchStr);
for ($i = 0; $i < count($plates); $i++) {
for ($j = 1; $j < 13; $j++) {
if(abs($searchInt - strToInt($plates[$i][$j])) < $minDiff) {
$minDiff = abs($searchInt - strToInt($plates[$i][$j]));
$minYear = $plates[$i][0];
$minKey = $plates[$i][$j];
}
}
}
return [$minYear, $minKey];
}
print_r(find('KHW'));

Answer 2

The code down below is by no means optimized, but it's rather a concept of how you might solve your problem.
//Flatten out array (one dimension without years and ----)
$flatten = array();
foreach($plates as $platevalues) {
foreach($platevalues as $pv) {
if ($pv != '---' && $pv != '----' && intval($pv) == 0) {
//Create a string only if valid letters included in the $letters-array
//This string is then added to the new array that is flattened out
$pv2 = '';
for($i=0;$i<strlen($pv);$i++) {
$letter = substr($pv,$i,1);
if (in_array($letter, $letters) !== false) {
$pv2 .= $letter;
}
}
$flatten[] = $pv2;
}
}
}
//Do the search
$search = 'GWN';
$search_result = '';
//Create a new search string based on first found in flattened
//plates array (first G, then GW, then GWN)
for($i=0;$i<strlen($search);$i++) {
foreach($flatten as $key=>$f) {
if (substr($search,0,$i+1) == substr($f,0,$i+1)) {
$search_result .= substr($search,$i,1);
break;
}
}
}
/*
$search_result is: GW
*/
//Create a new array where all items that begins with GW are included
$result = [];
foreach($flatten as $key=>$item) {
if (substr($search_result,0,strlen($search_result)) ==
substr($item,0,strlen($search_result))) {
$result[] = $item;
}
}
/*
$result =
array (size=2)
0 => string 'GWC' (length=3)
1 => string 'GWV' (length=3)
*/
//Create an array with total ASCII-value for each item
//in the $result array above
$result_o = [];
foreach($result as $item) {
$o = 0;
for($i=0;$i<strlen($item);$i++) {
$o += ord(substr($item,$i,1));
}
$result_o[]= $o;
}
/*
$result_o =
array (size=2)
0 => int 225
1 => int 244
*/
//Get the total ASCII-value for the original search string
$search_o = 0;
for($i=0;$i<strlen($search);$i++) {
$search_o += ord(substr($search,$i,1));
}
/*
$search_ o = 236
*/
//Find closest value in the $result_o (ASCII) - array compared (225,244)
//to the original $search_o ASCII value above (236)
$closest = 0;
$use_key = 0;
foreach($result_o as $key=>$item) {
if ($closest == 0 || abs($search_o - $closest) > abs($item - $search_o)) {
$closest = $item;
$use_key = $key;
}
}
/*
$closest = 244 (it's closer to 236 than 225 is)
$use_key = 1
*/
To get the result you have:
/*
$result =
array (size=2)
0 => string 'GWC' (length=3)
1 => string 'GWV' (length=3)
*/
//This should print out GWV
echo 'result=' . $result[$use_key];