delete pics to save space

2.12569.cpp

@@ -0,0 +1,120 @@
+#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;
+}