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| #include "iostream"
#include "algorithm"
#include "cstring"
#include "cstdio"
#include "cmath"
#include "vector"
#include "map"
#include "set"
#include "queue"
using namespace std;
#define MAXN 106
#define rep(i, a, b) for (int i = (a), i##end = (b); i <= i##end; ++i)
#define per(i, a, b) for (int i = (a), i##end = (b); i >= i##end; --i)
#define pii pair<int,int>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define vi vector<int>
#define all(x) (x).begin() , (x).end()
#define mem( a ) memset( a , 0 , sizeof a )
typedef long long ll;
#define P 1000000007
int n , d;
typedef double db;
struct Point {
db x , y;
Point( db x = 0 , db y = 0 ) : x(x) , y(y) {}
} A[MAXN] ;
db G[MAXN][MAXN];
inline Point operator + ( const Point& a , const Point& b ) {
return Point( a.x + b.x , a.y + b.y );
}
inline Point operator - ( const Point& a , const Point& b ) {
return Point( a.x - b.x , a.y - b.y );
}
inline db det( const Point& a , const Point& b ) {
return a.x * b.y - a.y * b.x;
}
const int maxe = 100006;
int head[maxe] , to[maxe] , nex[maxe] , wto[maxe] , ecn = -1;
void ade( int u , int v , int w ) {
to[++ ecn] = v , nex[ecn] = head[u] , wto[ecn] = w , head[u] = ecn;
to[++ ecn] = u , nex[ecn] = head[v] , wto[ecn] = 0 , head[v] = ecn;
}
int s , t;
queue<int> Q;
int dep[MAXN] , cur[MAXN];
const int inf = 1e9;
bool bfs( ) {
Q.push( s );
rep( i , 1 , n + 4 ) cur[i] = head[i];
memset( dep , 0x3f , sizeof dep );
dep[s] = 0;
while( !Q.empty() ) {
int u = Q.front(); Q.pop();
for( int i = head[u] ; ~i ; i = nex[i] ) if( dep[to[i]] > inf && wto[i] )
dep[to[i]] = dep[u] + 1 , Q.push( to[i] );
}
return dep[t] < inf;
}
ll dfs( int u , ll lim ) {
if( !lim || u == t ) return lim;
ll flow = 0 , f;
for( int& i = cur[u] ; ~i ; i = nex[i] ) if( dep[to[i]] == dep[u] + 1 && ( f = dfs( to[i] , min( lim , 1ll * wto[i] ) ) ) ) {
lim -= f , flow += f , wto[i] -= f , wto[i ^ 1] += f;
if( !lim ) break;
}
return flow;
}
ll dinic( ) {
ll res = 0;
while( bfs( ) )
res += dfs( s , 0x3f3f3f3f3f3f3f3f );
return res;
}
db dist( Point a , Point b ) {
return sqrt( ( a.x - b.x ) * ( a.x - b.x ) + ( a.y - b.y ) * ( a.y - b.y ) );
}
vi re; int res , vis[MAXN] , ok[MAXN];
void dfs( int u ) {
vis[u] = 1;
for( int o = head[u] ; ~o ; o = nex[o] ) if( wto[o] ) {
if( !vis[to[o]] ) dfs( to[o] );
}
}
void solve() {
cin >> n >> d;
rep( i , 1 , n ) {
static int x , y;
scanf("%d%d",&x,&y);
A[i].x = x , A[i].y = y;
}
rep( i , 1 , n ) rep( j , i + 1 , n ) G[i][j] = G[j][i] = dist( A[i] , A[j] );
rep( i , 1 , n ) rep( j , i + 1 , n ) if( G[i][j] <= d ) {
db r = G[i][j];
Point f = A[i] - A[j];
vi Gl , Gr;
int tot = 0;
rep( k , 1 , n ) if( G[i][k] <= r && G[j][k] <= r && i != k && j != k ) {
if( det( A[k] - A[j] , f ) > 0 ) Gl.pb( k ) , ++ tot;
else Gr.pb( k ) , ++ tot;
}
rep( k , 0 , n + 4 ) head[k] = -1 , vis[k] = 0;
ecn = -1;
for( int x : Gl ) for( int y : Gr ) if( G[x][y] > r )
ade( x , y , inf );
s = n + 1 , t = n + 2;
for( int x : Gl ) ade( s , x , 1 );
for( int y : Gr ) ade( y , t , 1 );
int ans = dinic( );
if( tot - ans + 2 <= res ) continue;
dfs( s );
re.clear();
re.pb( i ) , re.pb( j );
for( int o = head[s] ; ~o ; o = nex[o] ) {
int v = to[o];
if( vis[v] ) re.pb( v );
}
for( int o = head[t] ; ~o ; o = nex[o] ) {
int v = to[o];
if( !vis[v] ) re.pb( v );
}
res = re.size();
}
if( res <= 0 ) { cout << 1 << endl << 1 << endl; return; }
cout << res << endl;
for( int x : re ) printf("%d ",x);
}
signed main() {
solve();
}
|
