CareerCup

sample python code, language doesn't matter...

def hint(i,j,sudo_map) :
  ret = {}
  for p in range(1,10) :
    ret[p] = 1
  for y in range(9) :
    tmp = sudo_map[i][y]
    if tmp :
      ret[tmp] = 0
  for x in range(9) :
    tmp = sudo_map[x][j]
    if tmp :
      ret[tmp] = 0
  xc = int(i/3)
  yc = int(j/3)
  for x in range(xc*3,xc*3+3) :
    for y in range(yc*3,yc*3+3) :
      tmp = sudo_map[x][y]
      if tmp :
        ret[tmp] = 0
  return ret

nice code.
In short, what he is trying to do is:

1. Check the entire ith row and jth column and eliminate the possibilities of a number if it appears in these.
2. Repeat the same for the 3*3 square that (i,j) is part of nice.

Thanks.

Not all Sudoku is 9*9 large. Some easy ones are 2*3 and some difficult ones are 4*4.
Use two extra args to fit into more general cases.
(C# code)

public List<int> SudokuHint(int[,] board, Point p, int row, int col)