UVA 291 The House Of Santa Claus DFS

题目：

In your childhood you most likely had to solve the riddle of the house of Santa Claus. Do you remember that the importance was on drawing the house in a stretch without lifting the pencil and not drawing a line twice? As a reminder it has to look like shown in Figure 1.

Figure: The House of Santa Claus

Well, a couple of years later, like now, you have to ``draw'' the house
again but on the computer. As one possibility is not enough, we require
all the possibilities when starting in the lower left corner. Follow the example in Figure 2 while defining your stretch.

Figure: This Sequence would give the Outputline 153125432

All the possibilities have to be listed in the outputfile by increasing order, meaning that 1234... is listed before 1235... .

Output

So, an outputfile could look like this:

12435123
13245123
...
1512342

分析：
用5个点表示圣诞老人的房子，除了1-4和2-4两条边外，所有的边都相连，问能否从左下角（点1）一笔画出房子的路径有哪些，逐个点输出出来。
例如：
12435123
13245123
......
15123421
分析：
从点1开始，深搜遍历所有的边，直到遍历的边的个数达到8时递归结束。
AC code:

#include<bits/stdc++.h>
using namespace std;
int m[][];
void init()
{
    for(int i=;i<=;i++)
    {
        for(int j=;j<=;j++)
        {
            if(i!=j)    m[i][j]=;
            else m[i][j]=;
        }
    }
    m[][]=m[][]=;
    m[][]=m[][]=;
}
void dfs(int e,int k,string s)
{
    s+=(k+'');
    if(e==)
    {
        cout<<s<<endl;
        return;
    }
    for(int i=;i<=;i++)
    {
        if(m[k][i])
        {
            m[i][k]=m[k][i]=;
            dfs(e+,i,s);
            m[i][k]=m[k][i]=;
        }
    }
}
int main()
{
    init();
    dfs(,,"");
}