out< "please input the number of the nodes"<<endl cin>>nodesNum cout<<"pl

//1。应用回溯法时，所要求的解必须能表示成一个n-元组(x1,x2,x3----------xn),其中 xi取自某个有
//穷集Si。
//
//在编写隐式约束条件NextPosAbideByRule()的时候多次发生错误，花了很长时间才调试正确
//2。编写该函数规则：一定对每一个元素xi设立一个访问标志位vi，初试都为false，如果正在访问xi，
//就把vi设置为true;一旦要发生回溯到处理xi-1，就把vi还原为false。
#include<vector>
#include<iostream>
#include<cstdlib> //这个头文件包含了一些数学常用公式见c++标准程序库p582
using namespace std;

vector<int> chessBoard(20,0); //棋盘,以下标记录为行，其对应值为皇后所在的列数，值域为[1，n]
                               //从一开始计数,每个数字初试化为1
vector<bool> visited(20,false);


bool NextPosAbideByRule( int currentRow, int n)
{
	//如果返回的是false则要发生回溯
       //对第currentRow行放置皇后
	//判断列和对角线有没有重复
    if(!visited.at(currentRow))
	{
       chessBoard.at(currentRow) = 1;
	   visited.at(currentRow) = true;

	}
	else
		++chessBoard.at(currentRow);
	while( chessBoard.at(currentRow) <= n){
		bool overlap = false;
		int row;
		for( row = 1;row < currentRow; row++ )
		{
		   if((chessBoard.at(row) == chessBoard.at(currentRow))
			   || (abs(currentRow - row) == abs( chessBoard.at(currentRow) - chessBoard.at(row))))
			{
				overlap = true;
				break;
			}
		
		}//for
		if ( overlap == false) //如果符合条件
		{
			return true;
			visited.at(currentRow) = true;
		}
		else 
			++chessBoard.at(currentRow);

	}//while
    visited.at(currentRow) = false;//归位
	return false; //如果循环中跳出来


}

void OutPut( int n)
{   
	cout<<"--------------------------"<<endl;
	int i;
	for( i = 1; i <= n; ++i)
		cout<<" the colum of row " <<i<<" is " << chessBoard.at(i)<<endl;
   
}
int Queen( int n)
{
	//下标都是从1开始计数。
	// n行n列的棋盘上放置n个皇后，使得每两个皇后之间都不在同一行同一列或同一斜线上
	int answerNum = 0; //解的个数
	int workIndex = 1; //工作下标
	
	while( workIndex > 0 )
	{
		if( NextPosAbideByRule( workIndex,n ) )
		{
			if( workIndex == n)  //一条路径找到
			{ 
				if(answerNum < 10) 
				{
					OutPut(n);        //输出
				}
                 answerNum++;
			}
			else
				workIndex ++;
		}
		else
			workIndex --;
	}//while
	return answerNum;

}

int main()
{
	while(1){
		std::fill(chessBoard.begin(),chessBoard.end(),0);//重新赋值
		std::fill(visited.begin(),visited.end(),false);
		int line;
		cout<< "please input the lines you want to create a chessBoard "<<endl;
		cin >> line;
        int answerNum = Queen(line);
		cout<<"answer num:"<<answerNum<<endl;
	}
}