stack.php

stack.php

<?php 
class Stack {
  private $mins = array();
  private $arr = array();
  private $currentMin = null;
  
  private $size = 0;
  
  public function add($n) {
    $this->size++;
    
    if(is_null($this->currentMin) || $n < $this->currentMin) {
      $this->currentMin = $n;
    }
    
    $this->mins[] = $this->currentMin;
    $this->arr[] = $n;
  }
  
  public function pop() {
    if($this->size > 0) $this->size--;
    
    array_pop($this->mins);
    $mins = $this->mins;
    
    $this->currentMin = array_pop($mins);
    
    return array_pop($this->arr);    
  }
  
  function size() {
    return $this->size;    
  }
  
  public function getMin() {
    $mins = $this->mins;
    
    return array_pop($mins);
  }
}