Routing algorithm to minimization total cost
'Greedy' algorithm:

Assign nodes to the closest start node
Apply travelling salesman algorithm three times, once to each start node and its assigned nodes.

Optimize:

change random V to another start node
apply 'greedy' and keep change if better
repeat until all changes exhausted
The simple definition of my problem is as follows,
There are 3 start nodes[S] and 7[V] nodes that are to be visited.
There is a distance matrix for all the nodes comprising of distance of all the nodes from each other.
There will be a vehicle travelling from each start node to visit different nodes and return to their start node respectively. I need to minimize the overall distance covered by all three vehicles together.
Condition- all nodes that are to be visited[V] need to be visited once.
Every vehicle must return to their start node at the end of their trip.