Create a sudoku solution CHECKER
Python, 103

I hate sudoku.

b = [[1,2,3,4,5,6,7,8,9],
     [4,5,6,7,8,9,1,2,3],
     [7,8,9,1,2,3,4,5,6],
     [2,3,1,5,6,4,8,9,7],
     [5,6,4,8,9,7,2,3,1],
     [8,9,7,2,3,1,5,6,4],
     [3,1,2,6,4,5,9,7,8],
     [6,4,5,9,7,8,3,1,2],
     [9,7,8,3,1,2,6,4,5]]

e=enumerate;print 243-len(set((a,t)for(i,r)in e(b)for(j,t)in e(r)for a in e([i,j,i/3*3+j/3]*(0&lt;t&lt;10))))


How it works: each row, column, and block must have each number from 1 to 9.  So for each 0 &lt;= i, j &lt; 9, the cell i,j is in block 3*floor(i/3) + floor(j/3).  Thus, there are 243 requirements to satisfy.  I make each requirement a tuple ((item index,item type number),symbol) where item index is a number between 0 and 8 (inclusive), item type number is 0,1, or 2 to denote row, column or block respectively, and symbol is the entry b[i][j].

Edit: I mistakenly didn't check for valid entries.  Now I do.