function [indices, z] = get_sparse_vector(N, Amp)
    global K extend_target;
    z = zeros(N, 1);
    if extend_target
        target_start_idx = fix(0.4 * N);
        target_size = K;
        indices = target_start_idx: target_start_idx + target_size;
    else
        indices = randperm(N, K);
    end
    z(indices) = Amp;
end