高手帮忙看下这段代码，急（关于Heap和Priority Queue)
以下的代码是利用Heap来实现Priority Queue， Priority Queue的文件应该没有问题，只是调用这里的函数而已。当我调用ExtractMin（）的时候就会报错
#ifndef MIN_HEAP_H
#define MIN_HEAP_H
#include <vector>
using namespace std;
template <class T>
class min_heap
{
private:
vector<T> v;
int Parent (int index);
int LeftChild (int index);
int RightChild (int index);
void Heapify (vector<T>& vec, int index);
void Build_Heap();
public:
min_heap ();
void Insert (T value);
//void HeapSort ();
T ExtractMin ();
T Minimum ();
void PrintHeap ();
};
template <class T>
min_heap<T>::min_heap ()
{
v.resize(0);
}
template <class T>
int min_heap<T>::Parent (int index)
{
if (index%2 == 0)
return (index - 1)/2;
else
return index / 2;
}
template <class T>
int min_heap<T>::LeftChild (int index)
{
return 2 * index + 1;
}
template <class T>
int min_heap<T>::RightChild (int index)
{
return 2 * index + 2;
}
template <class T>
void min_heap<T>::Heapify (vector<T>& vec, int index)
{
int left = LeftChild (index);
int right = RightChild (index);
int smallest;
T temp;
if (left <= int(vec.size()) - 1) //debug的时候，到了这里会报segmentation fault
{
if (vec[left] < vec[index])
smallest = left;
else
smallest = index;
}
if (right <= int(vec.size()) - 1) //debug的时候，到了这里会报segmentation fault
if (vec[right] < vec[smallest])
smallest = right;
if (smallest != index)
{
temp = vec[index];
vec[index] = vec[smallest];
vec[smallest] = temp;
Heapify(vec, smallest);
}
}
template <class T>
void min_heap<T>::Build_Heap()
{
for (int i = (v.size()/2 - 1); i >= 0; i--)
Heapify(v, i);
}
template <class T>
void min_heap<T>::Insert (T value)
{
v.push_back(value);
int i = v.size() - 1;
while (i > 0 && v[Parent(i)] > value)
{
v[i] = v[Parent(i)];
i = Parent(i);
}
v[i] = value;
}
template <class T>
T min_heap<T>::ExtractMin ()
{
int smallest;
if (v.size() < 1)
cout << "Heap underflow" << endl;
else
{
smallest = v[0];
v[0] = v[v.size() - 1];
v.pop_back ();
Heapify(v, 0);
return smallest;
}
}
template <class T>
T min_heap<T>::Minimum ()
{
if(!v.empty())
return v[0];
else
cout << "The heap is empty.";
}
template <class T>
void min_heap<T>::PrintHeap ()
{
if (!v.empty())
{
for(int i = 0; i < int(v.size()); i++)
cout << v[i] << " ";
cout << endl;
}
else
cout << "The heap is empty.";
}
/*
template <class T>
void min_heap<T>::HeapSort ()
{
T temp;
Build_Heap();
for (int i = v.size() - 1; i >= 1; i--)
{
temp = v[0];
v[0] = v[i];
v[i] = temp;
v.pop_back ();
Heapify (v, 0);
}
}
*/
#endif // MIN_HEAP_H
