HDU 2181 哈密顿绕行世界问题

Sample Input

2 5 20

1 3 12

2 4 10

3 5 8

1 4 6

5 7 19

6 8 17

4 7 9

8 10 16

3 9 11

10 12 15

2 11 13

12 14 20

13 15 18

11 14 16

9 15 17

7 16 18

14 17 19

6 18 20

1 13 19

5

0

 

Sample Output

 

#include <iostream>

using namespace std;

int Map[21][21] = { 0 };  //邻接矩阵
int path[21];              //记录每一次答案的路线
bool visited[21] = { false };
int num = 1; //路径的编号


void dfs(int city, int cur) //city为当前访问的城市，已经访问了cur个城市
{
    path[cur] = city;    //将当前城市记录在路径上
    visited[city] = true;

    if (cur == 20)        //如果已经访问了20个城市
    {
        if (Map[city][path[1]] == 1)    //这个城市与起点城市之间存在路径
        {
            cout << num << ":  ";
            num++;
            for (int i = 1; i <= 20; ++i)    
                cout << path[i] << ' ';
            cout << path[1] << endl;
        }
    }

    for (int i = 1; i <= 20; ++i)
    {
        if (Map[i][city] == 1 && !visited[i])
        {
            dfs(i, cur+1);        //注意此处不能是++cur
            visited[i] = false;    //dfs完要把访问过的顶点重新置为未访问状态
        }
    }

}


int main()
{
    //创建邻接矩阵
    int city;
    for (int i = 1; i <= 20; ++i)
    {
        for (int j = 1; j <= 3; ++j)
        {
            cin >> city;
            Map[i][city] = 1;
        }
    }

    int m;
    while (cin >> m && m != 0)
    {
        dfs(m, 1);
        num = 1;
    }


    return 0;
    
}