In a heap with n elements with the smallest element at the root, the 7^th smallest element can be found in time

What is the weight of a minimum spanning tree of the following graph?

Ram and Shyam have been asked to show that a certain problem Π is NP-complete. Ram shows a polynomial time reduction from the 3-SAT problem to Π, and Shyam shows a polynomial time reduction from Π to 3-SAT. Which of the following can be inferred from these reductions ?

Let G = (V, E) be a directed graph with n vertices. A path from v_i to v_j in G is sequence of vertices (v_i, v_i+1, ……., v_j) such that (v_k, v_k+1) ∈ E for all k in i through j – 1. A simple path is a path in which no vertex appears more than once. Let A be an n x n array initialized as follow
$$$A[j,k] = \left\{ {\matrix{ {1\,if\,(j,\,k)} \cr {1\,otherwise} \cr } } \right.$$$ Consider the following algorithm.

for i = 1 to n
   for j = 1 to n
      for k = 1 to n
         A [j , k] = max (A[j, k] (A[j, i] + A [i, k]); 

Which of the following statements is necessarily true for all j and k after terminal of the above algorithm ?