QuadChoice.cc

#include<scil/scil.h>
#include<scil/core/monomial.h>

#define STRONG

#include <iostream>

using namespace SCIL;
using namespace std;

int main() {

  int num_vars,num_edges,num_cons;

  int i,j;
  double w;

  /* read data */

  cin>>num_vars>>num_edges>>num_cons;

  // variables

  ILP_Problem IP(Optsense_Min);
  vector<var> bvar(num_vars);
  for(int v = 0; v < num_vars; v++) {
    bvar[v] = IP.add_binary_variable(0);
  }

  // products
  for(int e = 0; e < num_edges; e++) {
    cin>>i>>j>>w;
    if(i < 1 || i > num_vars) {
      cerr<<"error in input: node "<<i<<" out of range!"<<endl;
      exit(1);
    }
    if(j < 1 || j > num_vars) {
      cerr<<"error in input: node "<<j<<" out of range!"<<endl;
      exit(1);
    }
    if(i == j) {
      cerr<<"error in input: loops not allowed!"<<endl;
      exit(1);
    }
    if(i < j) {
      IP.add_polynomial(bvar[i-1]*bvar[j-1]*w);
    }
    else {
      IP.add_polynomial(bvar[j-1]*bvar[i-1]*w);
    }
  }

  // choice constraints

  int s;
  vector<int> cvar(num_vars);
  for(int c = 0; c < num_cons; c++) {
    row r;
    cin>>s;
    for(int d = 0; d < s; d++) {
      cin>>cvar[d];
      r += bvar[cvar[d]-1];
    }
    IP.add_basic_constraint(r == 1.0,Static);

#ifdef STRONG
    for(int d1 = 0; d1 < s-1; d1++) {
      for(int d2 = d1+1; d2 < s; d2++) {
        row r;
        r = IP.add_polynomial(bvar[cvar[d1]-1]*bvar[cvar[d2]-1]* 0.);
        IP.add_basic_constraint(r == 0.0,Static);
      }
    }
#endif

  }

  /* solve ilp */

  // optimize

  IP.optimize();

  // print solution

  for(int v = 0; v < num_vars; v++) {
    if(IP.get_solution(bvar[v])>0.5) {
      cout<<"var "<<v<<endl;
    }
  }

  /* return */

  return 0;
}

---