Submission #704551

#	Time	Username	Problem	Language	Result	Execution time	Memory
704551		089487	Commuter Pass (JOI18_commuter_pass)	C++14	31 / 100	2037 ms	38968 KiB

commuter_pass

#pragma GCC optimzize("Ofast,no-stack-protector")
#include<bits/stdc++.h>
#define int long long
#define quick ios::sync_with_stdio(0);cin.tie(0);
#define rep(x,a,b) for(int x=a;x<=b;x++)
#define repd(x,a,b) for(int x=a;x>=b;x--)
#define lowbit(x) (x&-x)
#define sz(x) (int)(x.size())
#define F first
#define S second
#define all(x) x.begin(),x.end()
#define mp make_pair
#define eb emplace_back
using namespace std;
typedef complex<int> P;
#define X real()
#define Y imag()
typedef pair<int,int> pii;
void debug(){
    cout<<"\n";
}
template <class T,class ... U >
void debug(T a, U ... b){
    cout<<a<<" ",debug(b...);
}
const int N=2e5+7;
const int INF=1e18;
int dis[N];
int dis2[N];
vector<pii> v[N];
int in[N];
vector<pii> v2[N];
vector<int> From[N];
int D[301][301];
int p[N];
int sz[N];
void init(int n){
	rep(i,1,n){
		p[i]=i,sz[i]=1;
	}
}
int fp(int x){
	if(x!=p[x]) p[x]=fp(p[x]);
	return p[x];
}
void Union(int a,int b){
	a=fp(a);b=fp(b);
	if(a==b) return ;
	if(sz[a]<sz[b]) swap(a,b);
	sz[a]+=sz[b];
	p[b]=a;
}
vector<int> vec;
int s,e,f,t,n;
int ans=INF;
void solve(){
	vector<tuple<int,int,int> > rev;
	for(int i:vec){
		rev.eb(make_tuple(s,i,D[s][i]));
		rev.eb(make_tuple(e,i,D[e][i]));
		D[s][i]=D[i][s]=0;
		D[e][i]=D[e][i]=0;
	}
	fill(dis,dis+n+1,INF);
	dis[f]=0;
	priority_queue<pii,vector<pii>,greater<pii> > pq;
	pq.push(mp(0,f));
	while(sz(pq)){
		pii now=pq.top();
		pq.pop();
		if(dis[now.S]<now.F)  continue;
		rep(i,1,n){
			if(dis[i]>dis[now.S]+D[i][now.S]){
				pq.push(mp(dis[i]=dis[now.S]+D[i][now.S],i));
			}
		}
	}
	ans=min(ans,dis[t]);
	for(auto[a,b,c]:rev){
		D[a][b]=D[b][a]=c;
	}
}
bool invec[N];
void dfs(int now){
	if(invec[now]) return ;
	vec.eb(now);
	invec[now]=true;
	if(now==s){
		solve();
		vec.pop_back();
		invec[s]=false;
		return ;
	}
	for(int i=0;i<sz(From[now]);i++){
		 dfs(From[now][i]);
	}
	invec[now]=false;
	vec.pop_back();
}
signed main(){
	quick
	int m;
	cin>>n>>m;
	cin>>s>>e>>f>>t;
	if(n<=300){
		rep(i,1,n){
			rep(j,1,n) D[i][j]=INF;
		}
	}
	rep(i,1,m){
		int a,b,c;
		cin>>a>>b>>c;
		v[a].eb(mp(c,b));
		v[b].eb(mp(c,a));
		if(n<=300){
			D[a][b]=D[b][a]=min(D[a][b],c);
		}
	}
	fill(dis,dis+N,INF);
	fill(dis2,dis2+N,INF);
	dis[s]=0;
	priority_queue<pii,vector<pii> ,greater<pii> > pq;
	pq.push(mp(0,s));
	while(sz(pq)){
		pii now=pq.top();
		pq.pop();
		if(dis[now.S]<now.F) continue;
		for(pii p2:v[now.S]){
			if(dis[p2.S]>dis[now.S]+p2.F){
				pq.push(mp(dis[p2.S]=dis[now.S]+p2.F,p2.S));
			}
			if(n<=300&&dis[p2.S]==dis[now.S]+p2.F){
				From[p2.S].eb(now.S);
			}
		}
	}
	dis2[e]=0;
	pq.push(mp(0,e));
	while(sz(pq)){
		pii now=pq.top();
		pq.pop();
		if(dis2[now.S]<now.F) continue;
		for(pii p2:v[now.S]){
			if(dis2[p2.S]>dis2[now.S]+p2.F){
				pq.push(mp(dis2[p2.S]=dis2[now.S]+p2.F,p2.S));
			}
		}
	}
	if(n<=300){
		dfs(e);
		cout<<ans<<"\n";
		return 0;
	}
	init(n);
	Union(s,e);
	rep(i,1,n){
		if(dis[i]+dis2[i]==dis[e]){
			Union(i,e);
			v[s].eb(mp(0,i));
			v[i].eb(mp(0,s));
			v[e].eb(mp(0,i));
			v[i].eb(mp(0,e));
		}
	}
	fill(dis,dis+N,INF);
	dis[f]=0;
	pq.push(mp(0,f));
	while(sz(pq)){
		pii now=pq.top();
		pq.pop();
		if(dis[now.S]<now.F)  continue;
		for(pii p2:v[now.S]){
			if(dis[p2.S]>dis[now.S]+p2.F){
				pq.push(mp(dis[p2.S]=dis[now.S]+p2.F,p2.S));
			}
		}
	}
	cout<<dis[t]<<"\n";
	return 0;
}

Compilation message (stderr)

commuter_pass.cpp:1: warning: ignoring '#pragma GCC optimzize' [-Wunknown-pragmas]
    1 | #pragma GCC optimzize("Ofast,no-stack-protector")
      | 
commuter_pass.cpp: In function 'void solve()':
commuter_pass.cpp:62:10: warning: operation on 'D[e][i]' may be undefined [-Wsequence-point]
   62 |   D[e][i]=D[e][i]=0;
      |   ~~~~~~~^~~~~~~~~~
commuter_pass.cpp:79:10: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   79 |  for(auto[a,b,c]:rev){
      |          ^

• Subtask 1: 16 / 16
• Subtask 2: 15 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 45