-
Notifications
You must be signed in to change notification settings - Fork 0
/
SolveSudoku.m
58 lines (55 loc) · 1.56 KB
/
SolveSudoku.m
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
function solved = SolveSudoku(unsolvedBoard)
solved = solveSudoku(unsolvedBoard);
end
function solvedBoard = solveSudoku(board)
emptyInd = find(isnan(board));
solvedBoard = solverec(board, emptyInd, 1, false);
end
function candidates = getCandidates(board, row, col)
subrow = board(row, :);
subcol = board(:, col);
subSquareRow = (1:3) + 3 * (ceil(row / 3) - 1);
subSquareCol = (1:3) + 3 * (ceil(col / 3) - 1);
subBoard = board(subSquareRow, subSquareCol);
subBoard = subBoard(:);
refval = 1:9;
cdrow = setdiff(refval, subrow);
cdcol = setdiff(refval, subcol);
cdsqr = setdiff(refval, subBoard);
candidates = intersect(intersect(cdrow, cdcol), cdsqr);
end
function [res, solved, noSolutionFound] = solverec(board, emptyInd, ind, solved)
if nargin < 4; solved = false; end
noSolutionFound = false;
if ind > numel(emptyInd);
solved = true;
end
if solved
res = board;
return;
end
num = emptyInd(ind);
column = ceil(num / 9);
row = num - ((column - 1) * 9);
cd = getCandidates(board, row, column);
ncd = numel(cd);
if ncd == 0
noSolutionFound = true;
else
for k = 1:ncd;
board(num) = cd(k);
[res, solved, noSolutionFound] = solverec(board, emptyInd, ind + 1, solved);
if solved;
return;
end
if noSolutionFound
board(num) = NaN;
end
end
end
if noSolutionFound
board(num) = NaN;
res = board;
return
end
end