Just PHP FUN 013.

descendingOrder.php

<?php
# https://www.codewars.com/kata/5467e4d82edf8bbf40000155 Descending Order.
function descendingOrder(int $n): int {
  $array = array_map("intval",str_split($n));
  rsort($array);
  return intval(implode($array));
}

isIsogram.php

<?php
# https://www.codewars.com/kata/54ba84be607a92aa900000f1 Isograms.
function isIsogram($string) {
  $s = strtolower($string);
  $arr = str_split($s);
  $unique = array_unique($arr);
  return $arr == $unique;
}

just_php_fun_013.md

Just PHP FUN 013.

• https://www.codewars.com/kata/56dbe0e313c2f63be4000b25 Moves in squared strings (I). if (is_callable($f)) return $f($s);
• https://www.codewars.com/kata/5467e4d82edf8bbf40000155 Descending Order.
• https://www.codewars.com/kata/5d9f95424a336600278a9632 Sum of powers of 2.
• https://www.codewars.com/kata/5b0c0ec907756ffcff00006e Floating-point Approximation (III). If you don't know "catastrophic cancellation", you cannot resolve it. Terrence Xu
• https://www.codewars.com/kata/54ba84be607a92aa900000f1 Isograms.

Started at 02.06.2020 at 21:18 June Tuesday.
Finished at 02.06.2020 at 23:33 June Tuesday. (2hrs 15minutes)

power.php

<?php 
# https://www.codewars.com/kata/5d9f95424a336600278a9632 Sum of powers of 2.
// return an array of numbers (that are a power of 2)
// for which the input "n" is the sum
function powers($n) {
  $str = decbin($n); $answer = [];
  $arr = str_split($str); $arr = array_reverse($arr);
  foreach($arr as $i=>$x)
    if("1" == $x) array_push($answer, pow(2,$i));
  return $answer;
}

quadratic.php

<?php
# Unsolved yet.
# https://www.codewars.com/kata/5b0c0ec907756ffcff00006e Floating-point Approximation (III).
function quadratic($a, $b, $c) {
    $descr = $b*$b - 4*$a*$c;
    $x1 = (-1*$b + $descr)/(2*$a);
    $x2 = (-1*$b - $descr)/(2*$a);
    $x1 = abs($x1); $x2 = abs($x2);
    echo "Roots are: $x1 and $x2\n";
    return $x2;
    
}

squared_strings.php

<?php
# https://www.codewars.com/kata/56dbe0e313c2f63be4000b25 Moves in squared strings (I).
function vertMirror($s) {
    $arr = explode("\n",$s);
    return implode("\n",array_map("strrev",$arr));
}
function horMirror($s) {
    $arr = explode("\n",$s);
    return implode("\n",array_reverse($arr));
    
}
function oper($fct, $s) {
    return $fct($s);
}