View difference between Paste ID: iLwJQEF0 and SyWsrzSv

 <?php
 
 class LineSegment {
 	public $user_id;
 	public $start_point;
 	public $end_point;
 
 	public function __construct($user_id, $start_value, $end_value) {
 		$this->user_id = $user_id;
 		$this->start_point = new Endpoint($start_value, $user_id, TRUE);
 		$this->end_point = new Endpoint($end_value, $user_id, FALSE);
 	}
 
 	public function __toString() {
 		return "$user_id [{$start_point->value}, {$end_point->value}]";
 	}
 }
 
 class Endpoint {
 	public $value;
 	public $user_id;
 	public $is_start;
 
 	public function __construct($value, $user_id, $is_start) {
 		$this->value = $value;
 		$this->user_id = $user_id;
 		$this->is_start = $is_start;
 	}
 
 	public function __toString() {
 		$location = $this->is_start ? "start" : "end";
 		return "{$this->user_id}: {$this->value} ($location)";
 	}
 }
 
 class ResultSegment {
 	public $user_ids;
 	public $start_value;
 	public $end_value;
 
 	public $num_users;
 	public $duration;
 
 	public function __construct($user_ids, $start_value, $end_value) {
 		$this->user_ids = $user_ids;
 		$this->start_value = $start_value;
 		$this->end_value = $end_value;
 		$this->num_users = count($user_ids);
 		$this->duration = $end_value - $start_value; //assumption: values are numeric (insert your own function here)
 	}
 }
 
 class Sweepline {
 	public $last_endpoint_value; //value of last encountered endpoint
 	public $last_endpoint_was_end; //last encountered endpoint was an end (right) endpoint
 	public $active_users; //set of user IDs (user_id => user_id)
 	public $result_segments; //value-sorted array of LineSegments (with user_id being the number of available users)
 
 	public function __construct() {
 		$this->last_endpoint_value = 0;
 		$this->last_endpoint_was_end = false;
 		$this->active_users = array();
 	}
 
 	public function execute($endpoints) {
 		$this->result_segments = array();
 		foreach ($endpoints as $endpoint) {
 			$this->advance($endpoint);
 		}
 		return $this->result_segments;
 	}
 
 	public function advance(Endpoint $next_endpoint) {
-		echo "next endpoint: " . $next_endpoint, "\n";
+
 		if ($next_endpoint->is_start) {
 			$this->active_users[$user_id] = $user_id;
 		} else {
 			//when multiple segments end at the same value, you only need one result
 			if (!$this->last_endpoint_was_end) {
 				$result = new ResultSegment(array_values($this->active_users), $this->last_endpoint_value, $next_endpoint->value);
 				$this->result_segments[] = $result;
 			}
 			unset($this->active_users[$user_id]);
 		}
 		$this->last_endpoint_was_end = !$next_endpoint->is_start;
 		$this->last_endpoint_value = $next_endpoint->value;
 	}
 }
 
 
 function endpoint_comparer(Endpoint &$point1, Endpoint &$point2) {
 	if ($point1->value == $point2->value) {
 		if ($point1->is_start != $point2->is_start) {
 			return $point1->is_start ? -1 : 1; //ending points before starting
 		}
 	}
 	return $point1->value > $point2->value;
 }
 
 function result_comparer(ResultSegment &$line1, ResultSegment &$line2) {
 	if ($line1->num_users == $line2->num_users) {
 		return $line1->duration > $line2->duration;
 	}
 	return $line1->num_users > $line2->num_users;
 }
 
 
 //1) Create line-segments (assumption: for each line-segment, start_value is less than end_value)
 $segments = array(
 		new LineSegment(1, 10, 20),
 		new LineSegment(1, 40, 74),
 		new LineSegment(2, 19, 25),
 		new LineSegment(2, 34, 50),
 		new LineSegment(3, 15, 25),
 		new LineSegment(3, 55, 90),
 	);
 
 //1a) TODO: merge same-user segments that start/end at the same time.
 
 //2) create a sorted array of all endpoints (start and end)
 $endpoints = array();
 foreach ($segments as $segment) {
 	$endpoints[] = $segment->start_point;
 	$endpoints[] = $segment->end_point;
 }
 usort($endpoints, 'endpoint_comparer');
 
 //3) Initialize sweep-line
 $sweepline = new Sweepline();
 
 //4) Execute sweep-line
 $results = $sweepline->execute($endpoints);
 
 //5) Sort results
 usort($results, 'result_comparer');
 $results = array_reverse($results);
 
 
 echo "<pre>";
 print_r($results);
 echo "</pre>";