Just PHP FUN 004.

capitalize.php

<?php
# https://www.codewars.com/kata/59cfc000aeb2844d16000075 Alternate capitalization
function capitalize($s) {
  $a = "";
  $b = "";
  $arr = str_split($s);
  for($i = 0; $i <= count($arr); $i++){
    if(0 == $i%2){
      $a .= strtoupper($s[$i]);
      $b .= strtolower($s[$i]); 
    }else{
      $b .= strtoupper($s[$i]);
      $a .= strtolower($s[$i]);
    }
  }
  return [$a,$b];
}

crossover.php

<?php 
# https://www.codewars.com/kata/567d71b93f8a50f461000019 `Genetic Algorithm Series - #3 Crossover`.
function crossover($a, $b, $index) {
  var_dump([$a,$b,$index]); # <== interesting without this does not works.
  if(empty($a)) return ['',''];
  $a1 = substr($a,0,$index);
  $b1 = substr($b,0,$index);
  $a2 = substr($a,$index);
  $b2 = substr($b,$index);
  return [$a1.$b2, $b1.$a2];
}

# https://www.codewars.com/kata/567d71b93f8a50f461000019 `Genetic Algorithm Series - #3 Crossover`.
function crossover($a, $b, $index) {
  $a1 = substr($a,0,$index);
  $b1 = substr($b,0,$index);
  $a2 = substr($a,$index);
  $b2 = substr($b,$index);
  return [$a1.$b2, $b1.$a2];
}

generate.php

<?php
# Fails.
# https://www.codewars.com/kata/567d609f1c16d7369c000008/train/php
#  Genetic Algorithm Series - #1 Generate
function generate($length) {

  $x = str_pad(decbin(rand(0,intval(2**$length - 1))),$length,"0");
 //  var_dump($x);
  return $x;
}

# Works
function generate($length) {
  $ans = "";
  for($i=0; $i < $length; $i++) $ans .= strval(rand(0,1));
  return $ans;
}

growingPlant.php

<?php
# https://www.codewars.com/kata/58941fec8afa3618c9000184 Simple Fun #74: Growing Plan
function growingPlant($upSpeed, $downSpeed, $desiredHeight) {
   $size = 0;
   for($i = 1; $i < 50000; $i++){
     $size += $upSpeed;
     if($size >= $desiredHeight) return $i;
     $size -= $downSpeed;
   }
}

just_php_fun_004.md

Just PHP FUN 004.

• https://www.codewars.com/kata/5d5ee4c35162d9001af7d699 Sum of Minimums!
• https://www.codewars.com/kata/567b468357ed7411be00004a Genetic Algorithm Series - #4 Get population and fitnesses.
• https://www.codewars.com/kata/567b39b27d0a4606a5000057/solutions/php/all/best_practice Genetic Algorithm Series - #2 Mutation.
• https://www.codewars.com/kata/567d609f1c16d7369c000008/train/php Genetic Algorithm Series - #1 Generate.
• https://www.codewars.com/kata/567d71b93f8a50f461000019 Genetic Algorithm Series - #3 Crossover.
• https://www.codewars.com/kata/59cfc000aeb2844d16000075 Alternate capitalization.
• https://www.codewars.com/kata/58941fec8afa3618c9000184 Simple Fun #74: Growing Plant.

Started at 22.05.2020 21:27 Friday May.
Finished at 22.05.2020 22.15 1hr 12minutes.

map_population_fit.php

<?php
#  https://www.codewars.com/kata/567b468357ed7411be00004a `Genetic Algorithm Series - #4 Get population and fitnesses`.
function ($population, $fitness) {
  $f = function($x) use ($fitness) {
      return array("chromosome" => $x, "fitness" => $fitness($x));
    };
  return array_map(
    $f,
    $population
  );
}

mutate.php

<?php
# Genetic Algorithm Series - #2 Mutation
# https://www.codewars.com/kata/567b39b27d0a4606a5000057/solutions/php/all/best_practice 
function mutate($chromosome, $p) {
  $chromosome = str_split($chromosome);
  $funct = function($x) use ($p){ 
      $rnd = rand(1,1000)/1000;
      if($rnd <= $p) return "0" == $x ? "1" : "0" ;
      return $x;
    };
  $ans =  array_map($funct,$chromosome);
  return implode($ans);
}

sum_of_minimums.php

<?php
# https://www.codewars.com/kata/5d5ee4c35162d9001af7d699 Sum of Minimums!
function sum_of_minimums($numbers) {
  return array_sum(array_map('min', $numbers));
}