This Sudoku first time I saw in World Sudoku Championship 2009 (Puzzle L5). The difference in this from WSC puzzle is that in WSC puzzle both the diagonal should also 1 to 9 but in this puzzle there is no diagonal constraint. This puzzle I created for the Indian Team practice.
Neighbours Sudoku Puzzle Instructions:
Fill in the grid so that every row, every column and every 3x3 box contains all digits 1 through 9. The number outside the grid indicate neighboring digits in the specific row and column.
