Matlab N-Queen Problem
- by Kay
main.m
counter = 1;
n = 8;
board = zeros(1,n);
back(0, board);
disp(counter);
sol.m
function value = sol(board)
for ( i = 1:(length(board)))
for ( j = (i+1): (length(board)-1))
if (board(i) == board(j))
value = 0;
return;
end
if ((board(i) - board(j)) == (i-j))
value = 0;
return;
end
if ((board(i) - board(j)) == (j-i))
value = 0;
return;
end
end
end
value = 1;
return;
back.m
function back(depth, board)
disp(board);
if ( (depth == length(board)) && (sol2(board) == 1))
counter = counter + 1;
end
if ( depth < length(board))
for ( i = 0:length(board))
board(1,depth+1) = i;
depth = depth + 1;
solv2(depth, board);
end
end
I'm attempting to find the maximum number of ways n-queen can be placed on an n-by-n board such that those queens aren't attacking eachother. I cannot figure out the problem with the above matlab code, i doubt it's a problem with my logic since i've tested out this logic in java and it seems to work perfectly well there. The code compiles but the issue is that the results it produces are erroneous.
Java Code which works:
public static int counter=0;
public static boolean isSolution(final int[] board){
for (int i = 0; i < board.length; i++) {
for (int j = i + 1; j < board.length; j++) {
if (board[i] == board[j]) return false;
if (board[i]-board[j] == i-j) return false;
if (board[i]-board[j] == j-i) return false;
}
}
return true;
}
public static void solve(int depth, int[] board){
if (depth == board.length && isSolution(board)) {
counter++;
}
if (depth < board.length) { // try all positions of the next row
for (int i = 0; i < board.length; i++) {
board[depth] = i;
solve(depth + 1, board);
}
}
}
public static void main(String[] args){
int n = 8;
solve(0, new int[n]);
System.out.println(counter);
}
