Submission #189122

#	Time	Username	Problem	Language	Result	Execution time	Memory
189122		MvC	Tug of War (BOI15_tug)	C++11	23 / 100	164 ms	3068 KiB

tug

#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#define rc(x) return cout<<x<<endl,0
#define pb push_back
#define mkp make_pair
#define in insert
#define er erase
#define fd find
#define fr first
#define sc second
typedef long long ll;
typedef long double ld;
const ll INF=0x3f3f3f3f3f3f3f3f;
const ll llinf=(1LL<<62);
const int inf=(1<<30);
const int nmax=6e4+50;
const int mmax=2e6+50;
const int mod=1e9+7;
using namespace std;
int n,k,l[nmax],r[nmax],s[nmax],i,vl[nmax],cur,x,y,sa,sb,nx[nmax],rnx[nmax],nr,v[nmax],cnt;
vector<int>g[nmax],vc;
bitset<nmax>b;
bitset<mmax>f;
int dfs(int x)
{
	for(int i=0;i<(int)g[x].size();i++)
	{
		int y=g[x][i];
		if(b[y])continue;
		b[y]=1;
		if(!vl[y] || dfs(vl[y]))
		{
			vl[y]=x;
			return 1;
		}
	}
	return 0;
}
int main()
{
	//freopen("sol.in","r",stdin);
	//freopen("sol.out","w",stdout);
	//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
	ios_base::sync_with_stdio(false);cin.tie(0);cerr.tie(0);cout.tie(0);
	cin>>n>>k;
	for(i=1;i<=2*n;i++)
	{
		cin>>l[i]>>r[i]>>s[i];
		r[i]+=n;
		g[i].pb(l[i]);
		g[i].pb(r[i]);
	}
	for(i=1;i<=2*n;i++)
	{
		b.reset();
		if(!dfs(i))rc("NO");
	}
	for(i=1;i<=n;i++)nx[i]=r[vl[i]],rnx[r[vl[i]]]=i,sa+=s[vl[i]];
	for(i=n+1;i<=2*n;i++)nx[i]=l[vl[i]],rnx[l[vl[i]]]=i,sb+=s[vl[i]];
	cur=sa-sb;
	b.reset();
	for(i=1;i<=2*n;i++)
	{
		if(b[i])continue;
		x=i,nr++;
		while(!b[x])
		{
			v[x]=nr;
			b[x]=1;
			x=nx[x];
		}
		if(v[x]!=nr)continue;
		y=x,sa=sb=0,cnt=0;
		while(cnt<=2*n)
		{
			//assert((ld)clock()/CLOCKS_PER_SEC<=1.2);
			cnt++;
			if(x<=n)sa+=s[vl[x]];
			else sb+=s[vl[x]];
			x=rnx[x];
			if(x==y)break;
		}
		if(cnt>=2*n)continue;
		if(2*(sb-sa)>0)
		{
			cur+=2*(sb-sa);
			vc.pb(2*(sb-sa));
		}
		else vc.pb(-2*(sb-sa));
	}
	if(cur<-k)rc("NO");
	if(cur<=k)rc("YES");
	f[cur+k]=1;
	for(i=0;i<(int)vc.size();i++)
	{
		f|=(f>>vc[i]);
	}
	for(i=0;i<=2*k;i++)if(f[i])rc("YES");
	cout<<"NO"<<endl;
	return 0;
}

• Subtask 1: 0 / 18
• Subtask 2: 0 / 30
• Subtask 3: 23 / 23
• Subtask 4: 0 / 29