Before revision:  For this problem, we develop a heuristic algorithm which uses reweighted l1 minimization . We show through numerical simulations that the solutions calculated by our algorithm are close to optimal .
After revision:  For this problem, we develop a heuristic algorithm which uses reweighted l1 minimization algorithm and a greedy algorithm. We illustrate these two algorithms using three synthetic network structures for which the optimal solution can be calculated exactly. We also compare these two algorithms on three types random networks which are more complex .