Submission #1721265

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Source Code Expand

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
 
using namespace std;
using namespace __gnu_pbds;
 
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define fbo find_by_order
#define ook order_of_key
 
typedef long long ll;
typedef pair<ll,ll> ii;
typedef vector<int> vi;
typedef long double ld; 
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;
typedef set<int>::iterator sit;
typedef map<int,int>::iterator mit;
typedef vector<int>::iterator vit;
typedef pair<ld,ld> point;

const int N = 16;

ld dist[N][N];
point pt[N];
ld mst[(1<<N)];
ld dp[(1<<N)];
ld tot[N];
ld d(point x, point y)
{
	return sqrt((x.fi-y.fi)*(x.fi-y.fi) + (x.se-y.se)*(x.se-y.se));
}

struct DSU
{
	int S;
	
	struct node
	{
		int p; ll sum;
	};
	vector<node> dsu;
	
	DSU(int n)
	{
		S = n;
		for(int i = 0; i < n; i++)
		{
			node tmp;
			tmp.p = i; tmp.sum = 0;
			dsu.pb(tmp);
		}
	}
	
	void reset(int n)
	{
		dsu.clear();
		S = n;
		for(int i = 0; i < n; i++)
		{
			node tmp;
			tmp.p = i; tmp.sum = 0;
			dsu.pb(tmp);
		}
	}
	
	int rt(int u)
	{
		if(dsu[u].p == u) return u;
		dsu[u].p = rt(dsu[u].p);
		return dsu[u].p;
	}
	
	void merge(int u, int v)
	{
		u = rt(u); v = rt(v);
		if(u == v) return ;
		if(rand()&1) swap(u, v);
		dsu[v].p = u;
		dsu[u].sum += dsu[v].sum;
	}
	
	bool sameset(int u, int v)
	{
		if(rt(u) == rt(v)) return true;
		return false;
	}
	
	ll getstat(int u)
	{
		return dsu[rt(u)].sum;
	}
};

int n; 

void calcmst(int mask)
{
	DSU dsu(15);
	vector<pair<ld,ii> > vec;
	for(int i = 0; i < n; i++)
	{
		for(int j = 0; j < n; j++)
		{
			if(i==j) continue;
			if((mask&(1<<i))&&(mask&(1<<j)))
			{
				vec.pb(mp(dist[i][j],mp(i,j)));
			}
		}
	}
	sort(vec.begin(),vec.end());
	int cnt = __builtin_popcount(mask) - 1;
	ld ans = 0;
	for(int i = 0; i < vec.size(); i++)
	{
		//cerr<<"VEC : "<<vec[i].fi<<' '<<vec[i].se.fi<<' '<<vec[i].se.se<<'\n';
		if(dsu.sameset(vec[i].se.fi,vec[i].se.se))
		{
			continue;
		}
		cnt--;
		dsu.merge(vec[i].se.fi,vec[i].se.se);
		ans+=vec[i].fi;
	}
	assert(cnt==0);
	mst[mask] = ans;
}

int main()
{
	ios_base::sync_with_stdio(0); cin.tie(0);
	cin >> n;
	for(int i = 0; i < n; i++)
	{
		cin>>pt[i].fi>>pt[i].se>>tot[i];
		dp[(1<<i)] = tot[i];
	}
	for(int i = 0; i < n; i++)
	{
		for(int j = 0; j < n; j++)
		{
			dist[i][j] = d(pt[i],pt[j]);
			//cerr<<i<<' '<<j<<' '<<dist[i][j]<<'\n';
		}
	}
	for(int i = 1; i < (1<<n); i++) calcmst(i);
	mst[0] = 0;
	for(int i = 1; i < (1<<n); i++)
	{
		dp[i] = -mst[i];
		for(int j = 0; j < n; j++)
		{
			if(i&(1<<j)) dp[i]+=tot[j];
		}
		dp[i]/=ld(__builtin_popcount(i));
		//cerr<<i<<' '<<dp[i]<<' '<<mst[i]<<'\n';
		for(int j = i; j > 0; j = ((j-1)&i))
		{
			if(j == i) continue;
			dp[i] = max(dp[i], min(dp[j], dp[(i^j)]));
		}
	}
	cout<<fixed<<setprecision(12)<<dp[(1<<n) - 1]<<'\n';
}

Submission Info

Judge Result