import cp.
sudoku =>
instance(N,A),
A in 1..N,
foreach(Row in 1..N)
all_different([A[Row,Col] : Col in 1..N])
end,
foreach(Col in 1..N)
all_different([A[Row,Col] : Row in 1..N])
end,
M=floor(sqrt(N)),
foreach(Row in 1..M, Col in 1..M)
Square = [A[Row1,Col1] :
Row1 in (Row-1)*M+1..Row*M,
Col1 in (Col-1)*M+1..J*M],
all_different(Square)
end,
solve(A),
foreach(I in 1..N) write(A[I]) end.
instance(N,A) =>
N=9,
A={{5,3,_,_,7,_,_,_,_},
{6,_,_,1,9,5,_,_,_},
{_,9,8,_,_,_,_,6,_},
{8,_,_,_,6,_,_,_,3},
{4,_,_,8,_,3,_,_,1},
{7,_,_,_,2,_,_,_,6}}.