N-Queens II

Follow up for N-Queens problem.

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

此题虽然是N-Queens II ，但比N-Queens 简单！做细微改变即可！！

int totalNQueens(int n) {                int count = 0;        vector<int> res_one(n,-1);        solveNQueens(n,0,res_one,count);        return count;    }    void solveNQueens(int n,int level,vector<int> &res_one,int &count)    {    if (level >= n)    {    count++;     return ;    }    for (int i = 0;i < n;i++)    {    if (meet_condition(res_one,level,i))//未用的情况下    {    res_one[level] = i;    solveNQueens(n,level+1,res_one,count);        }    }    }