workforce1_c.c
/* Copyright 2021, 狗万app足彩Gurobi Optimization, LLC */ /*分配工人轮班;每个工人可能在某一天有空，也可能不在。如果问题无法解决，则使用IIS查找一组冲突的约束。请注意，除了通过IIS报告的内容之外，可能还有其他冲突。*/ #include #include #include #include "gurobi_c.h" #define xcol(w,s) nshift *w+s #define MAXSTR 128 int main(int argc, char *argv[]) {GRBenv *env = NULL;GRBmodel *model = NULL;Int error = 0, status;Int s, w, col;int *cbeg = NULL;int *cind = NULL; int idx; double *cval = NULL; char *sense = NULL; char vname[MAXSTR]; double obj; int i, iis, numconstrs; char *cname; /* Sample data */ const int nShifts = 14; const int nWorkers = 7; /* Sets of days and workers */ char* Shifts[] = { "Mon1", "Tue2", "Wed3", "Thu4", "Fri5", "Sat6", "Sun7", "Mon8", "Tue9", "Wed10", "Thu11", "Fri12", "Sat13", "Sun14" }; char* Workers[] = { "Amy", "Bob", "Cathy", "Dan", "Ed", "Fred", "Gu" }; /* Number of workers required for each shift */ double shiftRequirements[] = { 3, 2, 4, 4, 5, 6, 5, 2, 2, 3, 4, 6, 7, 5 }; /* Amount each worker is paid to work one shift */ double pay[] = { 10, 12, 10, 8, 8, 9, 11 }; /* Worker availability: 0 if the worker is unavailable for a shift */ double availability[][14] = { { 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1 }, { 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0 }, { 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1 }, { 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1 }, { 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1 }, { 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1 }, { 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 } }; /* Create environment */ error = GRBloadenv(&env, "workforce1.log"); if (error) goto QUIT; /* Create initial model */ error = GRBnewmodel(env, &model, "workforce1", nWorkers * nShifts, NULL, NULL, NULL, NULL, NULL); if (error) goto QUIT; /* Initialize assignment decision variables: x[w][s] == 1 if worker w is assigned to shift s. Since an assignment model always produces integer solutions, we use continuous variables and solve as an LP. */ for (w = 0; w < nWorkers; ++w) { for (s = 0; s < nShifts; ++s) { col = xcol(w, s); sprintf(vname, "%s.%s", Workers[w], Shifts[s]); error = GRBsetdblattrelement(model, "UB", col, availability[w][s]); if (error) goto QUIT; error = GRBsetdblattrelement(model, "Obj", col, pay[w]); if (error) goto QUIT; error = GRBsetstrattrelement(model, "VarName", col, vname); if (error) goto QUIT; } } /* The objective is to minimize the total pay costs */ error = GRBsetintattr(model, "ModelSense", GRB_MINIMIZE); if (error) goto QUIT; /* Make space for constraint data */ cbeg = malloc(sizeof(int) * nShifts); if (!cbeg) goto QUIT; cind = malloc(sizeof(int) * nShifts * nWorkers); if (!cind) goto QUIT; cval = malloc(sizeof(double) * nShifts * nWorkers); if (!cval) goto QUIT; sense = malloc(sizeof(char) * nShifts); if (!sense) goto QUIT; /* Constraint: assign exactly shiftRequirements[s] workers to each shift s */ idx = 0; for (s = 0; s < nShifts; ++s) { cbeg[s] = idx; sense[s] = GRB_EQUAL; for (w = 0; w < nWorkers; ++w) { cind[idx] = xcol(w, s); cval[idx++] = 1.0; } } error = GRBaddconstrs(model, nShifts, idx, cbeg, cind, cval, sense, shiftRequirements, Shifts); if (error) goto QUIT; /* Optimize */ error = GRBoptimize(model); if (error) goto QUIT; error = GRBgetintattr(model, "Status", &status); if (error) goto QUIT; if (status == GRB_UNBOUNDED) { printf("The model cannot be solved because it is unbounded\n"); goto QUIT; } if (status == GRB_OPTIMAL) { error = GRBgetdblattr(model, "ObjVal", &obj); if (error) goto QUIT; printf("The optimal objective is %f\n", obj); goto QUIT; } if ((status != GRB_INF_OR_UNBD) && (status != GRB_INFEASIBLE)) { printf("Optimization was stopped with status %i\n", status); goto QUIT; } /* do IIS */ printf("The model is infeasible; computing IIS\n"); error = GRBcomputeIIS(model); if (error) goto QUIT; printf("\nThe following constraint(s) cannot be satisfied:\n"); error = GRBgetintattr(model, "NumConstrs", &numconstrs); if (error) goto QUIT; for (i = 0; i < numconstrs; ++i) { error = GRBgetintattrelement(model, "IISConstr", i, &iis); if (error) goto QUIT; if (iis) { error = GRBgetstrattrelement(model, "ConstrName", i, &cname); if (error) goto QUIT; printf("%s\n", cname); } } QUIT: /* Error reporting */ if (error) { printf("ERROR: %s\n", GRBgeterrormsg(env)); exit(1); } /* Free data */ free(cbeg); free(cind); free(cval); free(sense); /* Free model */ GRBfreemodel(model); /* Free environment */ GRBfreeenv(env); return 0; }
