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Computerphile Sudoku Python

grid = [
       [ 5, 0, 0, 1, 0, 0, 7, 0, 0 ],
       [ 0, 2, 0, 0, 0, 7, 1, 0, 0 ],
       [ 3, 0, 1, 4, 0, 0, 8, 5, 2 ],
       [ 6, 1, 0, 5, 7, 2, 4, 0, 8 ],
       [ 0, 0, 2, 9, 6, 0, 0, 0, 0 ],
       [ 0, 4, 0, 0, 3, 0, 6, 2, 7 ],
       [ 4, 5, 9, 0, 8, 0, 0, 7, 0 ],
       [ 1, 3, 0, 0, 0, 0, 9, 8, 6 ],
       [ 2, 0, 0, 0, 1, 0, 0, 4, 3 ]
   ]
   
def possible(y,x,n):
   for i in range(0,9):
       if grid[y][i] == n:
           return False
   for i in range(0,9):
       if grid[i][x] == n:
           return False
   x0 = (x//3)*3
   y0 = (y//3)*3
   for i in range(0,3):
       for j in range(0,3):
           if grid[y0+i][x0+j] == n:
               return False
   return True
   
def solve():
   print("solving")
   for y in range(9):
       for x in range(9):
           if grid[y][x] == 0:
               for n in range(1,10):
                   if possible(y,x,n):
                       grid[y][x] = n
                       solve()
                       grid[y][x] = 0
               return
   printGrid()
   input()
   
def printGrid() : 
   for n in range(0,9):
       print(grid[n])
       
solve()

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