Task Manager (Priority Queue)
PHP
Hard
8 views
Problem Description
Commands: ADD name p, POP. POP removes and prints the task with highest priority; if tie, the one added earlier. If empty, print EMPTY.
Input Format
First line q. Next q lines.
Output Format
Outputs for POP.
Sample Test Case
Input:
7
POP
ADD clean 2
ADD build 5
ADD test 5
POP
POP
POP
Output:
EMPTY
build
test
clean
Official Solution
<?php
class TaskManager{
private $queue;
private $order=0;
function __construct(){
$this->queue=new SplPriorityQueue();
$this->queue->setExtractFlags(SplPriorityQueue::EXTR_DATA);
}
function addTask($name,$priority){
$this->queue->insert($name, [$priority, -$this->order]);
$this->order++;
}
function popTask(){
if($this->queue->isEmpty()) return null;
return $this->queue->extract();
}
}
$inputLines=preg_split('/\\R/', rtrim(stream_get_contents(STDIN)));
if(!$inputLines || trim($inputLines[0])==='') exit;
$q=intval($inputLines[0]);
$tasks=new TaskManager();
$output=[];
for($lineNo=1;$lineNo<=$q;$lineNo++){
$tokens=preg_split('/\\s+/', trim($inputLines[$lineNo] ?? ''));
$cmd=$tokens[0] ?? '';
if($cmd==='ADD'){
$tasks->addTask($tokens[1] ?? '', intval($tokens[2] ?? 0));
}else{
$name=$tasks->popTask();
$output[] = ($name===null) ? 'EMPTY' : $name;
}
}
echo implode(PHP_EOL,$output);
?>
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