P1726 上白泽慧音(0分)

  1 #include<iostream>
  2 #include<cstdio>
  3 #include<cstring>
  4 #include<cmath>
  5 #include<queue>
  6 #include<algorithm>
  7 using namespace std;
  8 const int MAXN=5001;
  9 void read(int &n)
 10 {
 11     char c=‘+‘;int x=0;bool flag=0;
 12     while(c<‘0‘||c>‘9‘)
 13     {c=getchar();if(c==‘-‘)flag=1;}
 14     while(c>=‘0‘&&c<=‘9‘)
 15     {x=x*10+c-48;c=getchar();}
 16     flag==1?n=-x:n=x;
 17 }
 18 struct node
 19 {
 20     int u,v,w,nxt;
 21 }edge[MAXN*4];
 22 int head[MAXN];
 23 int num=1;
 24 void add_edge(int x,int y,int z)
 25 {
 26     edge[num].u=x;
 27     edge[num].v=y;
 28     edge[num].w=z;
 29     edge[num].nxt=head[x];
 30     head[x]=num++;
 31 }
 32 bool have[MAXN][MAXN];
 33 int pre[MAXN];
 34 int nex[MAXN];
 35 int out[MAXN];
 36 void cler()
 37 {
 38     memset(have,0,sizeof(have));
 39     memset(pre,-1,sizeof(pre));
 40     memset(nex,-1,sizeof(nex));
 41 }
 42 int ans=0;
 43 int ansbg=0;
 44 int n,m;
 45 void calc_ans(int bg,int ed)
 46 {
 47     int num=0;
 48     int hh=ed;
 49     while(pre[ed]!=-1)
 50     {
 51         num++;
 52         ed=pre[ed];
 53     }
 54     num+=1;
 55     if(num>ans)
 56     {
 57         ans=num;
 58         ansbg=bg;
 59         for(int i=0;i<=n;i++)
 60             out[i]=nex[i];
 61     }
 62 }
 63 void dfs(int bg,int now)
 64 {
 65     for(int i=head[now];i!=-1;i=edge[i].nxt)
 66     {
 67         if(!have[now][edge[i].v])
 68         {
 69             if(edge[i].v==bg)
 70             {
 71                 calc_ans(bg,now);
 72                 return ;
 73             }
 74             have[now][edge[i].v]=1;
 75             have[edge[i].v][now]=1;
 76             pre[edge[i].v]=now;
 77             nex[now]=edge[i].v;
 78             dfs(bg,edge[i].v);
 79             have[now][edge[i].v]=0;
 80             have[edge[i].v][now]=0;
 81             pre[edge[i].v]=-1;
 82             nex[now]=-1;
 83         }
 84     }
 85 }
 86 int main()
 87 {
 88     
 89     read(n);read(m);
 90     for(int i=1;i<=n;i++)
 91         head[i]=-1;
 92     for(int i=1;i<=m;i++)
 93     {
 94         int x,y,how;
 95         read(x);read(y);read(how);
 96         if(how==1) add_edge(x,y,1);
 97         else {add_edge(x,y,1);add_edge(y,x,1);}
 98     }
 99     for(int i=1;i<=n;i++)
100     {
101         cler();
102         dfs(i,i);
103     }
104     printf("%d\n",ans);
105     if(ansbg)
106         printf("%d ",ansbg);
107     while(out[ansbg]!=-1)
108     {
109         ansbg=out[ansbg];
110         printf("%d ",ansbg);
111     }
112     return 0;
113 }