The Usage of Lambda and Heap in the C++ STL

Heap

In c++ STL, the heap had been implemented as the priority_queue.

Lambda with STL

To use decltype to inspects the declared type of an entity or the type and value category of an expression.

Code Example

// Using lambda to compare elements.
auto cmp = [](int left, int right) { return left < right;};
std::priority_queue<int, std::vector<int>, decltype(cmp)> heap(cmp);

Reference

http://en.cppreference.com/w/cpp/container/priority_queue