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;

    }

};