Leetcode no. 52

52. N-Queens II

Follow up for N-Queens problem.

Now, instead outputting board configurations, return the total number of distinct solutions.

public class Solution {
    int count=0;
    public int totalNQueens(int n){
        solveNQueens(0, 0, n, new int[n]);
        return count;
    }
    private void solveNQueens(int row, int col, int n, int[] column){
        if (row == n)
            count++;
        else{
            for (int i = col; i < n; i++) {
                column[row]= i;
                boolean f= true;
                for (int r = row-1, lc= i-1, rc= i+1; r>=0 ; r--,lc--,rc++ ) {
                    if (column[r]== i || column[r]==lc || column[r]==rc) f= false;
                }
                if (f) solveNQueens(row+1, 0, n, column);
            }
        }
    }
}