Suppose you are given an array s[1..n] and a procedure reverse (s, i, j) which reverse the order of elements in s between positions i and j (both inclusive). What does the following sequence do, where $$1 \le k < n:$$ reverse (s, 1, k);
reverse (s, k+1, n);
reverse (s, 1, n);

Let G be an undirected graph. Consider a depth-first traversal of G, and let T be the resulting depth-first search tree. Let u be a vertex in G and let v be the first new (unvisited) vertex visited after visiting u in the traversal. Which of the following statements is always true?

An n $$\times$$ n array v is defined as follows V [i, j] = i - j for all i, j, $$1 \le i \le n,\,1 \le j \le n$$ The sum of the elements of the array v is

Given relations r( w, x ) and s( y, z ), the result of

select distinct w,x
from r, s;

is guaranteed to be same as r, provided