(sudokuGraph[leftIndex][upIndex] == numberToCheck){                 return false;             }         }         return true;     }      public boolean notContainedInSubGrid(int leftIndex, int upIndex, int numberToCheck){         /* A peice of code that could definitely be improved. It is a successive if else ladder that check which grid a particular value is in. The logic is simple:         It assumes that each grid is bound by two indexes - one on the upper side and one on the left side. So if the cell was in the first grid, it's leftIndex would be less than three         and its upIndex would also be less than three. And so on. And as the ladder is if else, we don't need to define a greater than condition.*/         int boundLeftIndex = 0;         int boundUpIndex = 0;         if (leftIndex < 0 && upIndex < 0){             boundLeftIndex = 0;             boundUpIndex = 0;         }         else if (leftIndex < 0 && upIndex < 0){             boundLeftIndex = 0;             boundUpIndex = 0;         }         else if (leftIndex < 0 && upIndex < 0){             boundLeftIndex = 0;             boundUpIndex = 0;         }         else if (leftIndex < 0 && upIndex < 0){             boundLeftIndex = 0;             boundUpIndex = 0;         }         else if (leftIndex < 0 && upIndex < 0){             boundLeftIndex = 0;             boundUpIndex = 0;         }         else if (leftIndex < 0 && upIndex < 0){             boundLeftIndex = 0;             boundUpIndex = 0;         }         else if (leftIndex < 0 && upIndex < 0){             boundLeftIndex = 0;             boundUpIndex = 0;         }         else if (leftIndex < 0 && upIndex < 0){             boundLeftIndex = 0;             boundUpIndex = 0;         }         else if (leftIndex < 0 && upIndex < 0){             boundLeftIndex = 0;             boundUpIndex = 0;         }         