Exsists in PHP a function that change the order every time it loops?
I used: array_unshift() but it doesn't do the right job
Example:
1234 (row 1)
4123 (row 2)
3412 (row 3)
2341 (row 4)
Use array_pop to pop and get the element off the end of array, and array_unshift to prepend it to the beginning of the array, then repeat the process for $input iterations.
$input = 5;
$digits = range(1, $input);
for ($i=0; $i<$input; $i++) {
echo implode('', $digits), "\n";
array_unshift($digits, array_pop($digits));
}
Demo.
I am not sure if i have understood you correct but you can try the following:
$data = str_split('12345');
$n = 4;
for($i = 0; $i < $n; $i++) {
echo implode('', $data).'<br />'; //This is for demonstrating purposes
array_unshift($data, array_pop($data));
}
Result:
12345
51234
45123
34512
Related
I'd like the code to output index 6 since d is the starting point in terms of the longest identical consecutive portion in the string.
Not sure what I'm doing wrong here but it's currently returning 3 instead. Seems like I'm going in the right direction but something is missing but I can't pinpoint what.
Any feedback is appreciated! :)
$str = "abbcccddddcccbba";
$array = preg_split('/(.)(?!\1|$)\K/', $str);
$lengths = array_map('strlen', $array);
$maxLength = max($lengths);
$ans = array_search($maxLength, $lengths); // returns 3 but need it to return 6
echo $ans;
$lengths = array_map('strlen', $array);
Above line has only lengths of adjacent similar characters. array_search on max of those lengths will only yield the index where the maximum length is stored. It is totally unrelated with getting the index 6 of your string. If you still wish to get it, you will have to array_sum till that index to get the start index in the actual string.
Snippet:
<?php
$str = "abbcccddddcccbba";
$array = preg_split('/(.)(?!\1|$)\K/', $str);
$lengths = array_map('strlen', $array);
$maxLength = max($lengths);
array_splice($lengths,array_search($maxLength, $lengths));
$ans = array_sum($lengths);
echo $ans;
Online Demo
Alternate Solution:
I would write a simple for loop that uses 2 pointers to keep track of start index of similar characters and record the frequency and start index whenever it is greater than max frequency.
Snippet:
<?php
$str = "abbcccddddcccbba";
$len = strlen($str);
$maxF = 1;
$maxIdx = $startIdx = 0;
for($i = 1; $i < $len; ++$i){
if($str[ $i ] != $str[ $i - 1] || $i === $len - 1){
if($str[ $i ] === $str[ $i - 1] && $i === $len - 1) $i++;
if($maxF < $i - $startIdx){
$maxF = $i - $startIdx;
$maxIdx = $startIdx;
}
$startIdx = $i;
}
}
echo $maxIdx;
Online Demo
I am writing one logic to iterate numbers first and then additional logic to putting them into particular subset of array.
What does this code do :
Code accept first $n
its create array of $n number from 1 to $n
Then started converting to subset of $main_array to possible one like
['1'] [1,2] [1,2,3] [2] [2,3] [3] etc. same like this
After creating subset i am counting those some subset which satisfy condition
Condition is xyz[0] should not come in subset with abc[0] vice versa xyz[i] should not come in subset abc[i]. Example 2 and 3 is coming subset then dont count that subset, same 1 and 4 is coming then dont count
here is my nested for loop :
$n = 1299;
$main_array = range(1,$n);
$counter = 0;
$count = sizeof($abc); // $abc and $xyz size will same always.
$abc = [2,1];
$xyz = [3,4];
for ($i=0; $i <$n; $i++) {
for($j = $i;$j < $n; $j++){
$interval_array = array();
for ($k = $i; $k <= $j; $k++){
array_push($interval_array,$main_array[$k]);
}
$counter++;
for ($l=0; $l < $count ; $l++) {
//if block here to additional condition using in_array() php function. which do $counter--
if(in_array($abc[$l], $interval_array) &&
in_array($xyz[$l], $interval_array)){
$counter--;
break;
}
}
}
}
$main_array i have to create on the spot after receiving $n values.
Following is cases :
when running $n = 4 its run in 4s
when running $n = 1200 or 1299 or more than 1000 its run in 60s-123s
Expected execution timing is 9s. I reduce from 124s to 65s by removing function calling inside for loop but its not coming to point.
Expectation of code is if i have array like
$array = [1,2,3];
then
subset need to generate :
[1],[1,2],[1,2,3],[2],[2,3],[3]
Any help in this ?
It's difficult to test performance against your experience, but this solution removes one of the loops.
The way you repeatedly build $interval_array is not needed, what this code does is to just add the new value from the main array on each $j loop. This array is then reset only in the outer loop and so it just keeps the last values and adds 1 extra value each time...
for ($i=0; $i <$n; $i++) {
$interval_array = array();
for($j = $i;$j < $n; $j++){
array_push($interval_array,$main_array[$j]);
// Check output
echo implode(",", $interval_array)."\n";
$counter++;
for ($l=0; $l < $count ; $l++) {
if(in_array($abc[$l], $interval_array) &&
in_array($xyz[$l], $interval_array)){
$counter--;
break 2;
}
}
}
}
adding "\n" to better understanding for subset flow.
import datetime
N = list(range(1, int(input("N:")) + 1))
affected_list = list(map(int, input("affected_list").split()))
poisoned_list = list(map(int, input("poisoned_list").split()))
start_time = datetime.datetime.now()
exclude_list = list(map(list, list(zip(affected_list, poisoned_list))))
final_list = []
for i in range(0, len(N)):
for j in range(i + 1, len(N) + 1):
if N[i:j] not in exclude_list:
final_list.append(N[i:j])
print(final_list)
end_time = datetime.datetime.now()
print("Total Time: ", (end_time - start_time).seconds)
I want to print all combination of sub range in an given array. I have an array of y number of elements in it from which I want to print all combination of contiguous sub range.
Constraint is : each sub range should have at least 2 elements and each element in sub range should be contiguous. It should share same border of each element.
For example, We have an array of 7 elements [11,12,13,14,11,12,13]
So, the total number of sub range combination will [7 * (7-1) /2] = 21
So, the Output will be something like this:
11,12
12,13
13,14
14,11
11,12
12,13
11,12,13
12,13,14
13,14,11
...
11,12,13,14 and so on (total 21 combination as per above array)
we should not print any combination which is not contiguous. example: [11,12,14] is not valid combination as it skips the element "13" in between.
I am able to print the combination with 2 elements but i am having difficulty in printing more then 2 elements combination.
Below is what I have tried so far.
$data=array("11","12","13","14","11","12","13");
$totalCount=count($data);
for($i=0;$i<$totalCount;$i++){
if(($i+1) < ($totalCount)){
echo "[".$data[$i].",".$data[$i+1]."]<br>";
}
}
You can do that:
$arr = [11,12,13,14,11,12,13];
function genComb($arr, $from = 1, $to = -1) {
$arraySize = count($arr);
if ($to == -1) $to = $arraySize;
$sizeLimit = $to + 1;
for ($i = $from; $i < $sizeLimit; $i++) { // size loop
$indexLimit = $arraySize - $i + 1;
for ($j = 0; $j < $indexLimit; $j++) { // position loop
yield array_slice($arr, $j, $i);
}
}
}
$count = 0;
foreach (genComb($arr, 2) as $item) {
echo implode(',', $item), PHP_EOL;
$count++;
}
echo "total: $count\n";
Casimir et Hippolyte was faster, but you can gain huge performance by processing each contiguous section independently:
function getCombos(&$data) {
$combos = array();
$count = count($data);
$i = 0;
while ($i < $count) {
$start = $i++;
while ($i < $count && $data[$i - 1] + 1 == $data[$i]) // look for contiguous items
$i++;
if ($i - $start > 1) // only add if there are at least 2
addCombos($data, $start, $i, $combos); // see other answer
}
return $combos;
}
I have an array that I am looping through and breaking up into chunks of 50. However occasionally the number of items inside that array are more than what fits inside that chunk of 50 ex.:
$array = array(); // has 220 rows
for ($i = 0; $i < count($array); $i++) {
$j[] = $i;
if ($i % 50 == 1) {
print_r($j); // do something here with the 50 rows
$j = null;
}
}
The problem here is that this will not print anything after 201. I know there is some algebraic math involved in solving this but I am drawing a blank. Its times like these where I really wish I had paid attention in math class back in high school.
I think array_chunk fits up your requirement and no maths required.
$result_array = array_chunk($array, 50, true);
Add additional condition
if ($i % 50 == 1 || count($array)-1 == $i)
You just have to redeclare the array is my guess:
$array = array(); // has 220 rows
for ($i = 0; $i < count($array); $i++) {
$j[] = $i;
if ($i % 50 == 1) {
print_r($j); // do something here with the 50 rows
$j = array() ;
}
}
Once you perform $j = null there is no way you can do $j[] = $i
$array = array(); // has 220 rows
for ($i = 0; $i < count($array); $i++) {
$j[] = $i;
if ($i % 50 == 1) {
doSomething($j); // do something here with the 50 rows
$j = array(); // reset the array
}
}
doSomething($j); // with the last 20 entries
After your loop is finished, you will have the remaining 201 through 220 entries in $j, so just do your stuff again.
array_chunk
might be useful. Basically splits the array into chunks returning a multi dimensional array
I am trying to write a function that will replace characters in a string with their HTML entity encoded equivalent.
I want it to be able to go through all the possible combinations for the given string, for example:
go one-by-one
then combo i.e.. 2 at a time, then three at a time, till you get length at a time
then start in combo split, i.e.. first and last, then first and second to last
then first and last two, fist and second/third last
So for the characters "abcd" it would return:
abcd
abcd
abcd
abcd
abcd
abcd
abcd
abcd
abcd
abcd
abcd
abcd
etc.......... so on and so forth till there are no other combinations
Any ideas, or has anyone seen a function somewhere I could modify for this purpose?
loop from 0 to 2^length - 1. On each step, if Nth bit of the loop counter is 1, encode the Nth character
$str = 'abcd';
$len = strlen($str);
for($i = 0; $i < 1 << $len; $i++) {
$p = '';
for($j = 0; $j < $len; $j++)
$p .= ($i & 1 << $j) ? '&#' . ord($str[$j]) . ';' : $str[$j];
echo $p, "\n";
}
There are 2^n combinations, so this will get huge fast. This solution will only work as long as it fits into PHP's integer size. But really who cares? A string that big will print so many results you'll spend your entire life looking at them.
<?php
$input = 'abcd';
$len = strlen($input);
$stop = pow(2, $len);
for ($i = 0; $i < $stop; ++$i)
{
for ($m = 1, $j = 0; $j < $len; ++$j, $m <<= 1)
{
echo ($i & $m) ? '&#'.ord($input[$j]).';' : $input[$j];
}
echo "\n";
}
How about this?
<?php
function permutations($str, $n = 0, $prefix = "") {
if ($n == strlen($str)) {
echo "$prefix\n";
return;
}
permutations($str, $n + 1, $prefix . $str[$n]);
permutations($str, $n + 1, $prefix . '&#' . ord($str[$n]) . ';');
}
permutations("abcd");
?>