priority_queue

#include<vector>
using namespace std;
template <class T=int> 
class PriorityQueue
{
private:
	vector<int> Key;
	vector<T> element;
	vector<int>::iterator it;
	
	void insert(const T &value,const int &key ,const int l ,const int h)
	{
		if( h<=l )
		{
			if(Key.at(l)>= key )
			{
				it = element.begin();
				//it++;
				element.insert(it+l,value);
				it = Key.begin();
				//it++;
				Key.insert(it+l,key);
			}
			else
			{
				it = element.begin();
				it++;
				element.insert(it+l,value);
				it = Key.begin();
				it++;
				Key.insert(it+l,key);
			}
		}
		else
		{
			int mid = ( l + h ) / 2 ;
			if ( Key.at( mid ) == key )	// maybe queue have two element with same Priority 
			{
				it = element.begin();
				//it++;
				element.insert(it+mid,value);
				it = Key.begin();
				//it++;
				Key.insert(it+mid,key);
			} 
		    else if( Key.at( mid ) > key )
			{
				insert(value,key,l,mid-1 );
			}
			else if	( Key.at( mid ) < key )
			{
				insert(value,key,mid+1,h );
				
			}
			
		}
		
	}
public:
	PriorityQueue(const PriorityQueue& Copy)
	{
		Key = Copy.Key;
		element = Copy.element;
		
	}
	PriorityQueue operator=(const PriorityQueue& Copy)
	{
		Key = Copy.Key;
		element = Copy.element;
		return *this;
	}
	PriorityQueue()
	{
	}
	bool empty()
	{
		return element.empty();
	}
	int size()
	{
		return element.size();
	}
	void push(const T& value ,const int& key)
	{
		if(element.empty())
		{
			element.push_back(value);
			Key.push_back(key);
		}
		else
		{
			int s= element.size()-1;
			insert(value,key,0,s);
		}
	}
	T popLowestPriority()
	{
		
		T temp = element.at(0);
		it = element.begin();
		element.erase(it);
		it = Key.begin();
		Key.erase(it);
		return temp ;
	}
	T popHighestPriority()
	{
		
		T temp = element.back();
		element.pop_back();
		Key.pop_back();
		return temp ;
	}
	void changePriority(T value  , int newKey)
	{
		it = element.begin();
		int elementSize = element.size();
		for( int i = 0 ; i < elementSize ; i++ )
		{
			if( element.at( i ) == value )
			{
				element.erase( it+i);
				it = Key.begin();
				Key.erase(it+i);
				this->push(value,newKey);
			}
		}
	}
};