Employee Bus Allocation Algorithm -

my company started transportation employees. want build algorithm allocates employees bus based on bus stop.

no. of buses , bus routes fixed: ex:

(capacity:40) bus #1, ------ stop1 ----- stop3 ------- stop5 ----------     (capacity:50) bus #2, ------ stop2 ----- stop3 ------- stop6 ---------- stop5     (capacity:40) bus #3, ------ stop3 ----- stop4 

no. of employees availing transportation:

stop1: 10,     stop2: 10,     stop3: 20,     stop4: 18,     stop5: 20,     stop6: 10     

how can allocate optimal no. of employees buses?
there standard algorithm defines solution problem? googled couldnt find relevant algo this. please guide me in correct direction.

thanks in advance!

i think might end similar bin packing, knapsack , cutting stock, although not identical. problems np-hard, suspect problem too.

1. check if solvable: total(employees) < total (bus spaces)
2. for stops 1 bus serves: allocation space on bus. (e.g. stop 1,2,4,6 in example).

maybe:

1. sort stops number of buses serving stop.
2. allocate passengers first fit?