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  1. <?php
  2.  
  3.   $list = range(1,100);
  4.   unset($list[3]);
  5.   unset($list[31]);
  6.  
  7.   findMissing($list,1,100);
  8.  
  9.   function findMissing($list, $min, $max) {
  10.     if(empty($list)) {
  11.       print_r(range($min, $max));
  12.       return;
  13.     }
  14.  
  15.     $l = $r = [];
  16.     $pivot = array_pop($list);
  17.  
  18.     foreach($list as $number) {
  19.       if($number < $pivot) {
  20.         $l[] = $number;
  21.       }
  22.       else {
  23.         $r[] = $number;
  24.       }
  25.     }
  26.  
  27.     if(count($l) == $pivot - $min - 1) {
  28.       // only 1 missing number use difference of sums
  29.       print array_sum(range($min, $pivot-1)) - array_sum($l) . "\n";
  30.     }
  31.     else if(count($l) < $pivot - $min) {
  32.       // more than 1 missing number, recurse
  33.       findMissing($l, $min, $pivot-1);
  34.     }
  35.  
  36.     if(count($r) == $max - $pivot - 1) {
  37.       // only 1 missing number use difference of sums
  38.       print array_sum(range($pivot + 1, $max)) - array_sum($r) . "\n";
  39.     } else if(count($r) < $max - $pivot) {
  40.       // mroe than 1 missing number recurse
  41.       findMissing($r, $pivot+1, $max);
  42.     }
  43.   }
Success #stdin #stdout 0.02s 52432KB
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https://ideone.com/qY00Qn
language:
PHP (php 7.3.5)
created:
7 years ago
visibility:
public

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