Microsoft Software Developer interview questions

Given a set of 21 tasks = {A, B,....Z} except I, O, U, X and Q. Each task requires 4 hours of processing. Except for tasks E, Y, P, R, W that require 8 hours of processing. You have 3 machines to process these tasks = T1, T2, T3. T1 and T2 are available everyday for 8 hours. T3 is available only on Mon, Wed and Fri for 8 hours. You are given 3 lists that indicate the dependency list among the tasks. L1 = A->R->K->M (eg A can be completed if R is completed, R can be completed only if K is completed etc.) L2 = N->G->V->E->Z->H L3 = C->F->Y->D->J->P->T->S->W->B->C (cycle)