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  1. <?php
  2.  
  3. class Node {
  4.     public $question;
  5.     public $trueBranch;
  6.     public $falseBranch;
  7.  
  8.     public function __construct($question, $trueBranch, $falseBranch) {
  9.         $this->question = $question;
  10.         $this->trueBranch = $trueBranch;
  11.         $this->falseBranch = $falseBranch;
  12.     }
  13. }
  14.  
  15. class DiagnosisSystem {
  16.     private $tree;
  17.  
  18.     public function __construct($tree) {
  19.         $this->tree = $tree;
  20.     }
  21.  
  22.     public function diagnose() {
  23.         return $this->traverse($this->tree);
  24.     }
  25.  
  26.     private function traverse($node) {
  27.         if ($node instanceof Node) {
  28.             $answer = $this->askQuestion($node->question);
  29.             if ($answer) {
  30.                 return $this->traverse($node->trueBranch);
  31.             } else {
  32.                 return $this->traverse($node->falseBranch);
  33.             }
  34.         } else {
  35.             return $node;  // Leaf node (diagnosis)
  36.         }
  37.     }
  38.  
  39.     private function askQuestion($question) {
  40.         echo $question . " (yes/no): ";
  41.         $handle = fopen ("php://stdin","r");
  42.         $line = fgets($handle);
  43.         return trim($line) === 'yes';
  44.     }
  45. }
  46.  
  47. $tree = new Node('Do you have a fever?',
  48.     new Node('Do you have a cough?', 'You may have a flu.', 'You may have a fever.'),
  49.     new Node('Do you have a cough?', 'You may have a cold.', 'No diagnosis available.')
  50. );
  51.  
  52. $system = new DiagnosisSystem($tree);
  53. echo $system->diagnose();
  54.  
Success #stdin #stdout 0.02s 26104KB
comments (?)
stdin 
Standard input is empty
stdout 
Do you have a fever? (yes/no): Do you have a cough? (yes/no): No diagnosis available.
https://ideone.com/wfpMQc
language:
PHP (php 7.3.5)
created:
14 days ago
visibility:
public

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