Sudoku using Microsoft Solver Foundation

using Microsoft.SolverFoundation.Services;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Configuration;

namespace Sudoku
{
	public static class SudokuProblem
	{
		private static List<int> problem = new List<int>();
		private static List<int> solution = new List<int>();
		private static int hints = Properties.Settings.Default.Setting;

		public static bool IsSolved(List<int> possibleSolution)
		{
			if (possibleSolution == null)
			{
				return false;
			}

			for (int i = 0; i < possibleSolution.Count; i++)
			{
				if (possibleSolution[i] != solution[i])
				{
					return false;
				}
			}
			return true;
		}

		public static void GenerateSudoku()
		{
			SolverContext context = SolverContext.GetContext();
			Model model = context.CreateModel();

			List<Decision> decisionList = DecisionFactory.BuildDecisions(Grid.GetAllSquares());
			model.AddDecisions(decisionList.ToArray());

			// Add 27 constraints to model
			for (int j = 0; j < 9; j++)
			{
				model.AddConstraints("constraint_" + j,
						Model.AllDifferent(getDecision(decisionList, Grid.GetRow(j))),
						Model.AllDifferent(getDecision(decisionList, Grid.GetColumn(j))),
						Model.AllDifferent(getDecision(decisionList, Grid.GetRegion(j)))
				);
			}

			// Add seeds to model
			List<int> seedValues = Utils.GetUniqueRandomNumbers(1, 10, 9);
			for (int i = 0; i < 9; i++)
			{
				model.AddConstraints("seed_" + i.ToString(), decisionList[i] == seedValues[i]);
			}

			context.Solve(new ConstraintProgrammingDirective());
			solution = ConvertDecicionsToIntegers(decisionList);
		}

		public static void GenerateProblem()
		{
			GenerateSudoku();
			HideNumbers();
		}

		public static List<int> GetSolution()
		{
			return solution;
		}

		public static List<int> GetProblem()
		{
			return problem;
		}

		private static List<int> ConvertDecicionsToIntegers(List<Decision> decisionList)
		{
			List<int> results = new List<int>();
			foreach (Decision decision in decisionList)
			{
				results.Add(Convert.ToInt32(decision.ToString()));
			}
			return results;
		}

		private static Term[] getDecision(List<Decision> decisionList, List<int> indexes)
		{
			Term[] results = new Term[9];
			int i = 0;
			foreach (int index in indexes)
			{
				results[i] = (decisionList[index]);
				i++;
			}
			return results;
		}

		private static void HideNumbers()
		{
			List<int> toHide = Utils.GetUniqueRandomNumbers(0, Constants.BoardSize, Constants.BoardSize - hints);

			// Initialize problem to solution
			problem = new List<int>();
			problem.AddRange(solution);

			foreach (int hideMe in toHide)
			{
				problem[hideMe] = Constants.PlaceHolder;
			}
		}

		public static bool HasUniqueSolution()
		{
			SolverContext context = SolverContext.GetContext();
			context.ClearModel();
			Model model = context.CreateModel();

			List<Decision> decisionList = DecisionFactory.BuildDecisions(Grid.GetAllSquares());
			model.AddDecisions(decisionList.ToArray());

			// Add 27 constraints to model
			for (int j = 0; j < 9; j++)
			{
				model.AddConstraints("constraint_" + j,
						Model.AllDifferent(getDecision(decisionList, Grid.GetRow(j))),
						Model.AllDifferent(getDecision(decisionList, Grid.GetColumn(j))),
						Model.AllDifferent(getDecision(decisionList, Grid.GetRegion(j)))
				);
			}

			// Add all hints as constraints
			for (int i = 0; i < problem.Count; i++)
			{
				if (problem[i] != 0)
				{
					// This is a hint
					model.AddConstraints("hint_" + i.ToString(), decisionList[i] == problem[i]);
				}
			}

			List<DecisionBinding> decisionBindings = new List<DecisionBinding>();
			for (int i = 0; i < problem.Count; i++)
			{
				if (problem[i] == 0) // This is hidden square
				{
					DecisionBinding binding = decisionList[i].CreateBinding();
					decisionBindings.Add(binding);
				}
			}
			context.FindAllowedValues(decisionBindings);
			foreach (DecisionBinding decisionBinding in decisionBindings)
			{
				if (decisionBinding.Int32FeasibleValues.ToList().Count > 1)
				{
					
					return false;
				}
			}
			return true;
		}
	}
}