title: Constructing a priority queue of vectors
body: <p>I am looking for a simple STL implementation of a priority queue of vectors. Each vector has exactly 4 elements. I want to sort my priority queue on the basis of the 3rd element of each vector. The vector with the lowest 3rd element should come at the top(min priority queue of vectors).</p>
  
  <p>How to implement this in C++?</p>
  
  <p>Also, if anybody has the actually STL implementation of default priority queue, please provide a link. Like the official implementation inside the STL.</p>