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  1. <?php
  2. function palindrome_array($n, $to_str = false) {
  3.     if( ($n = (int)$n) == 0 ) return false;
  4.     $half = ceil($n / 2);
  5.     $is_odd = $n % 2;
  6.     $output = [];
  7.     for($i = 0, $k = 0; $i < $n; $i++) {
  8.         $output[] = $i < $half ? ++$k : ($is_odd ? --$k : $k--);    
  9.     }
  10.     return $to_str ? implode('', $output) : $output ;
  11. }
  12.  
  13. print_r( palindrome_array(4) );
  14. print_r( palindrome_array(5, true) );
Success #stdin #stdout 0.02s 52472KB
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stdin
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Standard input is empty
stdout
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Array
(
    [0] => 1
    [1] => 2
    [2] => 2
    [3] => 1
)
12321
https://ideone.com/rXmzba
language:
PHP (php 7.3.5)
created:
8 years ago
visibility:
secret

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