void FloydWarshall(TwoDIntArray &DistanceMatrix, 
                   TwoDIntArray &PredecessorMatrix, int cities) {         

   int DistAdder;
   for (int k=0; k<cities; k++) {
      for (int i=0; i<cities; i++) {
         for (int j=0; j<cities; j++) {            
            DistAdder = DistanceMatrix(i, k) + DistanceMatrix(k, j);
            if( DistAdder < DistanceMatrix(i, j)) {                  
               DistanceMatrix(i, j) = DistAdder;                   // Update distance matrix
               PredecessorMatrix(i, j) = PredecessorMatrix(k, j);  // Update predecessor matrix
            }  
         }
      }
   }
}