使用STL make_heap / push_heap / pop_heap时的无效堆

Question

我为std::make_heap / push_heap /pop_heap编写了简单的包装器：

template <typename T, typename Cont = std::vector<T>, typename Compare = std::less<typename Cont::value_type> >  
class Heap  
{  
public:  
    inline void init() { std::make_heap(m_data.begin(), m_data.end(), Compare()); }  
    inline void push(const T & elm) { m_data.push_back(elm); std::push_heap(m_data.begin(), m_data.end(), Compare()); }  
    inline const T & top() const { return m_data.front(); }  
    inline void pop() { std::pop_heap(m_data.begin(), m_data.end(), Compare()); m_data.pop_back(); }  

private:  
    Cont m_data;  
};  

我用的是：

class DeliveryComparator
{
public:
    bool operator()(Delivery * lhs, Delivery * rhs)
    {
        if(lhs->producer != rhs->producer) return *lhs->producer < *rhs->producer;  
        if(lhs->rate == rhs->rate) return lhs->diff < rhs->diff;  
        return lhs->rate < rhs->rate; 
    }
};

Heap<Delivery*, std::vector<Delivery*>, DeliveryComparator> packages; 

但有时我会收到无效的堆std调试消息。我只是通过正确的堆方法使用堆。当消息发生时，m_data不是空的。

堆有什么问题？

*我使用MSVS2010

Answer 1

在编辑了堆的数据后(除了那些有待添加的数据)，堆被销毁了。如果下一步使用push_heap()方法，则将抛出此异常。您应该使用make_heap()而不是push_heap()。例如(顺便说一下，下面的示例是我的程序中的代码片段)：

if (highHeap[0] < solvedQuestions){ 
               lowHeap[lenghOfLowHeap++] = highHeap[0]; // *It only add a new item without destroy the heap 
               highHeap[0] = solvedQuestions;
               // Update the Heap
               push_heap(lowHeap, lowHeap + lenghOfLowHeap); 
               //push_heap(highHeap, highHeap + lenghOfHighHeap, greater<int>()); // invalid heap exception. Because the heap was destroyed by "highHeap[0] = solvedQuestions;"
               make_heap(highHeap, highHeap + lenghOfHighHeap, greater<int>());
           }