注意一个景点只能去一次。
#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>
#include <cmath>
using namespace std;
int n, m, xx[205], yy[205], hea[205], ss, tt, cnt, lev[205], maxFlow;
const int oo=0x3f3f3f3f;
queue<int> d;
struct Edge{
int too, nxt, val;
}edge[45005];
double dis(int i, int j){
return sqrt((xx[i]-xx[j])*(xx[i]-xx[j])+(yy[i]-yy[j])*(yy[i]-yy[j]));
}
void add_edge(int fro, int too, int val){
edge[cnt].nxt = hea[fro];
edge[cnt].too = too;
edge[cnt].val = val;
hea[fro] = cnt++;
}
void addEdge(int fro, int too, int val){
add_edge(fro, too, val);
add_edge(too, fro, 0);
}
bool bfs(){
memset(lev, 0, sizeof(lev));
lev[ss] = 1;
d.push(ss);
while(!d.empty()){
int x=d.front();
d.pop();
for(int i=hea[x]; i!=-1; i=edge[i].nxt){
int t=edge[i].too;
if(!lev[t] && edge[i].val>0){
lev[t] = lev[x] + 1;
d.push(t);
}
}
}
return lev[tt]!=0;
}
int dfs(int x, int lim){
if(x==tt) return lim;
int addFlow=0;
for(int i=hea[x]; i!=-1 && addFlow<lim; i=edge[i].nxt){
int t=edge[i].too;
if(lev[t]==lev[x]+1 && edge[i].val>0){
int tmp=dfs(t, min(lim-addFlow, edge[i].val));
edge[i].val -= tmp;
edge[i^1].val += tmp;
addFlow += tmp;
}
}
return addFlow;
}
void dinic(){
while(bfs()) maxFlow += dfs(ss, oo);
}
int main(){
memset(hea, -1, sizeof(hea));
cin>>n>>m;
for(int i=1; i<=n+m; i++) scanf("%d %d", &xx[i], &yy[i]);
ss = 0; tt = n + m + 1;
for(int i=1; i<=n; i++){
addEdge(ss, i, 1);
if(i==n) break;
double disii=dis(i, i+1);
for(int j=n+1; j<=n+m; j++)
if(dis(i,j)+dis(j,i+1)<disii*2.0+1e-7)
addEdge(i, j, 1);
}
for(int j=n+1; j<=n+m; j++)
addEdge(j, tt, 1);
dinic();
cout<<n+maxFlow<<endl;
for(int i=1; i<=n; i++){
printf("%d %d ", xx[i], yy[i]);
for(int j=hea[i]; j!=-1; j=edge[j].nxt){
if(edge[j^1].val && edge[j].too!=ss){
int t=edge[j].too;
printf("%d %d ", xx[t], yy[t]);
}
}
}
return 0;
}