最大堆 yongmou

#ifndef MAXHEAP_H
#define MAXHEAP_H


template<class T>
class MaxHeap{
    T * heap;        //heap[1...]
    int size;
    int max_size;
public:
    MaxHeap(int max_size);
    ~MaxHeap(){ delete [] heap;}

public:
    bool empty();//true if the heap is empty
    bool full(); //true if the heap is full
    T top();     //return the max element

    bool insert(const T& item);
    void deleteMax();//delete the max element
};

template<class T>
MaxHeap<T>::MaxHeap(int max_size){
    heap = new T[max_size+1];
    this->max_size = max_size;
    size = 0;
}

template<class T>
bool MaxHeap<T>::empty(){
    return (size == 0);
}

template<class T>
bool MaxHeap<T>::full(){
    return (size == max_size);
}

template<class T>
T MaxHeap<T>::top(){
    return heap[1];//heap[0]没有用
}

template<class T>
bool MaxHeap<T>::insert(const T& item){
    if(size == max_size)
        return false;
    int i;
    size++;
    i = size;
    while((i != 1) && (item > heap[i/2])){
        heap[i] = heap[i/2];
        i /= 2;
    }
    heap[i] = item;       
}

template<class T>
void MaxHeap<T>::deleteMax(){
    if(size == 0)
        return ;
    int parent, child;
    T tmp = heap[size];
    size--;
    parent = 1;
    child = 2;
    while(child <= size){
        /* find the larger child of the current parent*/
        if((child < size) && (heap[child] < heap[child+1]))
            child++;
        if(tmp >= heap[child])
            break;
        /* move to the next lower level*/
        heap[parent] = heap[child];
        parent = child;
        child *= 2;
    }
    heap[parent] = tmp;

}


#endif