I have seen lots of solutions confuse priority queue with heap. I find a good  and list the talk below.

Concept:

1.Heap is a kind of data structure. It is a name for a particular way of storing data that makes certain operations very efficient. We can use a tree or array to describe it.

18  /	\ 10	 16/ \   / \9  5  8  1218, 10, 16, 9, 5, 8, 12

2.Priority queue is an abstract datatype. It is a shorthand way of describing a particular interface and behavior, and says nothing about the underlying implementation.

A heap is a very good data structure to implement a priority queue. The operations which are made efficient by the heap data structure are the operations that the priority queue interface needs.

Implementation: c++

1.priority_queue: 

struct compare {    bool operator()(const ListNode* l, const ListNode* r) {        return l->val > r->val;    }};ListNode *mergeKLists(vector
     
       &lists) { //priority_queue    priority_queue
      
       , compare> q;    for(auto l : lists) {        if(l)  q.push(l);    }    if(q.empty())  return NULL;    ListNode* result = q.top();    q.pop();    if(result->next) q.push(result->next);    ListNode* tail = result;                while(!q.empty()) {        tail->next = q.top();        q.pop();        tail = tail->next;        if(tail->next) q.push(tail->next);    }    return result;}
      
     

2.make_heap:

static bool heapComp(ListNode* a, ListNode* b) {        return a->val > b->val;}ListNode* mergeKLists(vector
     
      & lists) { //make_heap    ListNode head(0);    ListNode *curNode = &head;    vector
      
        v;       for(int i =0; i
       
         heap data strcture    while(v.size()>0){        curNode->next=v.front();        pop_heap(v.begin(), v.end(), heapComp);         v.pop_back();         curNode = curNode->next;        if(curNode->next) {            v.push_back(curNode->next);             push_heap(v.begin(), v.end(), heapComp);        }    }    return head.next;}