在boost :: heap :: priority_queue中推送結構對象時發生錯誤

Question

我有一個結構，其對象將被推入boost::heap::priority_queue 。

typedef struct
{
  int i, j;
  double deltaQ;

} heapNode;

int main()
{
    double a[] = {0.03, 0.01, 0.04, 0.02, 0.05};
    heapNode node;

    boost::heap::priority_queue<heapNode> maxHeap;
    for(int  i = 0; i < 5; i++)
    {
        node.deltaQ = a[i];
        node.i = i;
        node.j = i;
        maxHeap.push(node);//error
    }

    for(int i = 0; i < 5; i++)
    {
        node = maxHeap.top();
        cout << node.deltaQ << " " << node.i << " " << node.j;
        cout << "\n";
        maxHeap.pop();
    }
}

此代碼給出了一個編譯器錯誤，

error: no match for 'operator<' (operand types are 'const heapNode' and 'const heapNode')|

任何解決方案，我使用的是codeBlocks 16.01。

謝謝

Answer 1

您需要為heapNode對象提供比較操作。

a）定義operator<作為heapNode的成員

struct heapNode
{
  int i, j;
  double deltaQ;

  bool operator<(const heapNode& theOther) const {
      // your comparison operation
    return this->deltaQ < theOther.deltaQ;
  }
};

b）您可以將functor對象作為比較器傳遞給priority_queue構造函數

explicit priority_queue(value_compare const & = value_compare());

定義函子

struct cmp {
   bool operator () (const heapNode& lhs, const heapNode& rhs) const {
     return lhs.deltaQ < rhs.deltaQ;
   }
};

將其傳遞給priority_queue的ctor

cmp c;
boost::heap::priority_queue<heapNode,boost::heap::compare<cmp>> maxHeap{c};

Answer 2

在您的heapNode結構中，您需要重載operator < 。

struct HeapNode
{
  int i, j;
  double deltaQ;
  bool operator<(const HeapNode& other)
  {
     *return true if current HeapNode is less than other, else false*
  };

} heapNode;

http://en.cppreference.com/w/cpp/language/operators將是您的入門指南。