/* PB constraints to enforce assignment of exactly one color. */
for (int i = 0; i < numberOfVertices; i++) {
IVecInt literals = new VecInt(colors);
IVec<BigInteger> coefficients = new Vec<BigInteger>(colors);
for (int j = 1; j <= colors; j++) {
literals.push(i * colors + j);
coefficients.push(BigInteger.ONE);
}
solver.addPseudoBoolean(literals, coefficients, false,
BigInteger.ONE);
solver.addPseudoBoolean(literals, coefficients, true,