There may be large number of coordinates (sparsely, dense also) so we have to make sure the solution is efficient. Definitely better than O(n^2). The starter code given is as follows:

Consider a 2D game that uses path nodes for AI navigation. From any node, AI may walk to any othe node that is within 9 units, but no farther. Multiple nodes may be traversed in sequence to create a path. Some modes are marked as AI spawners. Given a list of node positions, eliminate all of the nodes that the AI cannot path to starting from any spawner node. Return a sorted list of the indices of nodes that remain. Sample input spawner nodes- 0,0 100, .20 200.0 -50, .500 10, 0, 10 10, 10 200.5 Sample output 0,2, 4, 5, 6, 7 Consider a 2D game that uses path nodes for AI navigation. From any node, AI may walk to any othe node that is within 9 units, but no farther. Multiple nodes may be traversed in sequence to create a path. Some modes are marked as AI spawners. Given a list of node positions, eliminate all of the nodes that the AI cannot path to starting from any spawner node. Return a sorted list of the indices of nodes that remain. Sample input spawner nodes- 0,0 100, .20 200.0 -50, .500 10, 0, 10 10, 10 200.5 Sample output 0,2, 4, 5, 6, 7