//AssignNodes is used for assigning nodes into different specific shards
func AssignNodes(nodes []Address, shardSize int, randoms []int) (int, [][]Address) {
	numNodes := len(nodes)                        //the number of participating nodes
	numShard := numNodes / shardSize              //the number of shards
	copies := []Address{}                         //the copies of nodes awaiting assignment
	copies = append(copies, nodes...)             //copy the participting nodes
	shards := AllocateShards(shardSize, numShard) //create a dynamic slice storing different shards
	for i := 0; i < numNodes; i++ {               //loop over the random numbers
		shardIndex := i / shardSize                   //the index of the shard for assignment
		nodeIndex := i % shardSize                    //index of the node within the assigned shard
		currentNumNodes := len(copies)                //the current number of not yet assigned nodes
		selectedIndex := randoms[i] % currentNumNodes //select a node index from the not yet assigned nodes
		selectedNode := copies[selectedIndex]         //the address of the node to be assigned
		shards[shardIndex][nodeIndex] = selectedNode  //assign to the specified shard
		copies = append(copies[:i], copies[i+1:]...)  //update the nodes waiting for assignment
	}
	return numShard, shards
}