//        //  main.cpp        //  EightQueens        //        //  Created by liujan on 10/24/14.        //  Copyright (c) 2014 liujan. All rights reserved.        //                #include <iostream>        #include "stack"        using namespace std;        bool isvisited[30][30];        int Count = 0;        int n;                //判断是否可以从当前位置移动到x,y这个位置        bool canMove(int x, int y){            if (isvisited[x][y])                return false;            for (int i = 0; i < n; i++){                for (int j = 0; j < n; j++){                    if (isvisited[i][j] && abs(x-i) == abs(y-j))  //对角线或已经访问过                        return false;                    else if(isvisited[x][j]) {  //相同行                        return false;                    }                    else if (isvisited[i][y]) //相同列                        return false;                }            }            return true;        }                //移动到下一位置        bool moveQueens(int x, int y){            if (Count == n){  //走完最后一个节点，则输出结果                for (int i = 0; i < n; i++){                    for (int j = 0; j < n; j++) {                        if (isvisited[i][j])                            cout << 1 << " ";                        else                            cout << 0 << " ";                    }                    cout << endl;                }                cout << endl;                return true;            }            else {                for (int i = y; i < n; i++){                    if (canMove(x, i)){                        isvisited[x][i] = true;                        Count ++;                        moveQueens(x+1, 0);                                    isvisited[x][i] = false;  //回溯                        Count --;                    }                }                return false;            }        }                        int main(int argc, const char * argv[]) {            while(cin >> n){                if (n <= 0 )                    continue;            // insert code here...                for (int i = 0; i < n; i++)                    for (int j = 0; j < n; j++)                        isvisited[i][j] = false;                Count = 0;                moveQueens(0,0);            }            return 0;        }