% 
% FUNCTION 10.2 : "cp1002_select_nodes"
%
% This function selects a target node and k reference nodes
% from a set of nodes.
% The function receives in input:
% - The total number of nodes N
% - The number of reference nodes k
% The function returns:
% - The ID of the target node Nx
% - A vector Refs of length k, containing the ID of the
%   reference nodes 
%
% Programmed by Luca De Nardis
%
function [Nx,Ref] = cp1002_select_nodes(N,k);

% Extraction of the target node
Nx = ceil(N*rand);

Check=zeros(1,N);

for i=1:k
    Ref(i) = Nx;
    % Check: is Ref(i) different from Nx? 
    while((Ref(i)==Nx)||(Ref(i)==0))
        Ref(i)= ceil(N*rand);
        % Check: is Ref(i) already selected?
        if(Check(Ref(i)))
            Ref(i) = 0;
        else
            Check(Ref(i))=1;
        end
    end
end