leetcode[52]N-Queens II

Follow up for N-Queens problem.

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

class Solution {
public:
void init(vector<string> &temp, int n)
{
    string strtemp(n,'.');
    temp.insert(temp.end(),n,strtemp);
    return;
}
bool checkij(vector<string> &temp, int i, int j)
{
    for (int ii=i-1,jleft=j-1;ii>=0&&jleft>=0;ii--,jleft--)
    {
        if(temp[ii][jleft]=='Q')return false;
    }
    for (int ii=i-1,jright=j+1;ii>=0&&jright<temp.size();ii--,jright++)
    {
        if(temp[ii][jright]=='Q')return false;
    }
    for (int k=0;k<temp.size();k++)
    {
        if (k!=j&&temp[i][k]=='Q')return false;
        if (k!=i&&temp[k][j]=='Q')return false;
    }
    return true;
}
bool solveOne(int &res,vector<string> &temp,int n, int index)
{
    if(index==n)
    {
        res++;
        return true;
    }
    for (int j=0;j<n;j++)
    {
        temp[index][j]='Q';
        if (checkij(temp,index,j))
        {
            solveOne(res,temp,n,index+1);
        }
        temp[index][j]='.';    
    }
}
    int totalNQueens(int n) {
        int res=0;
        vector<string> temp;
        init(temp,n);
        for(int i=0;i<n;i++)
        {
            temp[0][i]='Q';
            solveOne(res,temp,n,1);
            temp[0][i]='.';
        }
        return res;
    }
};