def BFS(G):
     queue = []
     visited = [ 0 for i in range(len(G)) ]
     queue.append(0)
     visited[0] = 1
     while len(queue) > 0:
          current = queue.pop(0)
          print(current, end=" ")
          for j in range(len(G)):
               if G[current][j] == 1 and visited[j] == 0:
                    visited[j] = 1
                    queue.append(j)

BFS([ [0,0,1,0,1,1,0], [0,0,1,1,0,1,0], [1,1,0,1,1,1,0], [0,1,1,0,0,0,0], 
      [1,0,1,0,0,0,1], [1,1,1,0,0,0,0], [0,0,0,0,1,0,0] ])