Just PHP FUN 012.

arrayLeaders.php

<?php
# https://www.codewars.com/kata/5a651865fd56cb55760000e0 Array Leaders (Array Series #3).
function arrayLeaders($numbers) {
  $size = count($numbers); $answer = [];
  $sum = 0;
  for($j = $size - 1; $j >= 0; $j -= 1){
    if($numbers[$j] > $sum) array_unshift($answer,$numbers[$j]);
    $sum += $numbers[$j];
  }
  return $answer;
}

divisors.php

<?php
# https://www.codewars.com/kata/542c0f198e077084c0000c2e Count the divisors of a number.
function divisors($n) {
  $sum = 0;
  for($i = 1; $i <= $n; $i += 1)
  if(0 == $n%$i) $sum +=1 ;
  return $sum;
}

DNA_strand.php

<?php
# https://www.codewars.com/kata/554e4a2f232cdd87d9000038 Complementary DNA.
function DNA_strand($dna) {
  $mp = ["A"=>"T","T"=>"A","C"=>"G","G"=>"C"];
  return implode(array_map(function($x) use($mp){ return $mp[$x];},str_split($dna)));
}
# ----------------------------------------------------------
function DNA_strand($dna) {
  return strtr($dna,"ATCG","TAGC");
}

just_php_fun_012.md

Just PHP FUN 012.

• https://www.codewars.com/kata/5a523566b3bfa84c2e00010b Minimize Sum Of Array (Array Series #1).
• https://www.codewars.com/kata/5a651865fd56cb55760000e0 Array Leaders (Array Series #3).
• https://www.codewars.com/kata/542c0f198e077084c0000c2e Count the divisors of a number.
• https://www.codewars.com/kata/554e4a2f232cdd87d9000038 Complementary DNA.
• https://www.codewars.com/kata/56e9e4f516bcaa8d4f001763 Sum of numbers from 0 to N.

Started at 01.06.2020 19:23 Monday June.
Finished at 01.06.2020 21:31 Monday June. (2hrs 08minutes)

minSum.php

<?php
# https://www.codewars.com/kata/5a523566b3bfa84c2e00010b Minimize Sum Of Array (Array Series #1).
function minSum($arr) {
  sort($arr); $sum = 0;
  $i = 0; $j = count($arr) - 1;
  while( $i < $j){
    $sum += $arr[$i] * $arr[$j];
    $i += 1; $j -= 1;
  }
  return $sum;
}

SequenceSum.php

<?php
# https://www.codewars.com/kata/56e9e4f516bcaa8d4f001763 Sum of numbers from 0 to N.
class SequenceSum {
  public function showSequence($count) {
     if($count < 0) return "$count<0";
     if(0 == $count) return "0=0";
     $sum = ($count*(1+$count))/2;
     $line = implode(range(0,$count),"+");
     return "$line = $sum";
  }
}