消防车 Firetruck【DFS】

传送门
水题。。。
$DFS$扫描结点

#include
using namespace std;
const int maxn=22;
int g[maxn][maxn];
int p[maxn];
int aim;
int vis[maxn];
int cnt;
int dfs(int u,int *a,int cur){
    if(u==aim){
        for(int i=0;i<cur;i++)
        printf("%d ",a[i]);
        ++cnt;
        cout<<'\n';
    }
    else for(int v=2;v<maxn;v++){
        if(g[u][v]&&!vis[v]) {
          a[cur]=v;
          vis[v]=1;
          dfs(v,a,cur+1);
          vis[v]=0;
        }
    }
}

int main(){
    int a,b;
    while(cin>>aim){
        memset(g,0,sizeof g);
        cnt=0;
    while(scanf("%d%d",&a,&b),a,b){
        g[a][b]=1;
        g[b][a]=1;
        memset(vis,0,sizeof(vis));
    }
    p[0]=1;
    dfs(1,p,1);
    printf("There are %d routes from the firestation to streetcorner %d.\n",cnt,aim);
    }
}