【leetcode】N-Queens II

N-Queens II

Follow up for N-Queens problem.

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

 

class Solution {
public:
    int totalNQueens(int n) {
        vector<int> q(n,-1);
        int result=0;
        getQueens(0,n,result,q);
        return result;
    }
   
    void getQueens(int level,int &n,int &result,vector<int> &q)
    {
        if(level==n)
        {
            result++;
            return;
        }
        bool flag=false;
        for(int i=0;i<n;i++)
        {
            q[level]=i;
            if(isValid(q,level))
            {
                getQueens(level+1,n,result,q);
            }
            q[level]=-1;
        }
    }
   
   
    bool isValid(vector<int> &q,int &level)
    {
 
        for(int i=0;i<level;i++)
        {
            if(q[i]==q[level]||abs(q[level]-q[i])==abs(level-i)) return false;
        }
       
        return true;
    }
 
};