pop_heap(stack,stack+ct,cmp);
stack[ct-1] = s[i].q;
push_heap(stack,stack+ct,cmp);


         // stack[0]=s[i].q;
         // pop_heap(stack,stack+ct,cmp);
         // push_heap(stack,stack+ct,cmp);

这两段代码等效么？怎么都能过？pop_heap不是把最后一个元素加到堆头，然后 shift_down 么？