Files
OI-source/2.12569.cpp
2023-08-03 09:22:52 +08:00

121 lines
1.9 KiB
C++

#include<cstdio>
#include<cstring>
using namespace std;
struct node
{
int pos,st,step,pre;
node(){}
node(int _p,int _st,int _step)
{
pos=_p;
st=_st;
step=_step;
}
};
bool had_answer,G[20][20],vis[20][1<<17];
int n,m,s,t,res,head,tail,kase;
node st;
node que[20<<17];
void init()
{
memset(&st,0,sizeof(st));
memset(G,0,sizeof(G));
memset(vis,0,sizeof(vis));
head=tail=1;
scanf("%d%d%d%d",&n,&m,&s,&t);
int x,y;
for(int i=0;i<m;i++)
{
scanf("%d",&x);
st.st|=1<<x;
}
st.pos=s;
st.st|=1<<s;
for(int i=0;i<n-1;i++)
{
scanf("%d%d",&x,&y);
G[x][y]=G[y][x]=1;
}
}
int stk[10000],top;
inline int lowbit(int n)
{
return n&(-n);
}
inline int count(int n)
{
int res=0;
while(n)
{
res++;
n>>=1;
}
return res;
}
void print(int n)
{
top=0;
while(n!=0)
{
stk[top++]=que[n].st;
n=que[n].pre;
}
while(top>1)
{
int x=stk[top-1]^stk[top-2],a=count(lowbit(x))-1,b=count(lowbit(x&~lowbit(x)))-1;
if(stk[top-1]&1<<a) printf("%d %d\n",a,b);
else printf("%d %d\n",b,a);
top--;
}
}
void solve()
{
if(s==t)
{
printf("Case %d: 0\n\n",++kase);
return;
}
que[tail++]=st;
vis[st.pos][st.st]=1;
while(tail-head>0)
{
int st=que[head].st;
for(int i=1;i<=n;i++)
for(int j=1;j<=n;j++)
if(i!=j&&G[i][j]&&((st&1<<i)>>i)&&!((st&1<<j)>>j))
{
que[tail].pos=(i==que[head].pos?j:que[head].pos);
que[tail].pre=head;
que[tail].step=que[head].step+1;
que[tail].st=(st&(~(1<<i)))|1<<j;
if(vis[que[tail].pos][que[tail].st]) continue;
vis[que[tail].pos][que[tail].st]=1;
if(que[tail].pos==t)
{
printf("Case %d: %d\n",++kase,que[tail].step);
print(tail);
printf("\n");
return;
}
tail++;
}
head++;
}
printf("Case %d: -1\n\n",++kase);
}
int main()
{
// printf("%d %d %d\n",count(0),count(1),count(2));return 0;
#ifdef local
freopen("pro.in","r",stdin);
#endif
int t,kase=0;
scanf("%d",&t);
while(t-->0)
{
init();
solve();
}
return 0;
}