Submission #346846

#	Time	Username	Problem	Language	Result	Execution time	Memory
346846		CSQ31	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	438 ms	25708 KiB

commuter_pass

#pragma GCC optimize("Ofast") 
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define sz(a) (int)(a.size())
#define all(a) a.begin(),a.end()
#define lb lower_bound
#define ub upper_bound
#define owo ios_base::sync_with_stdio(0);cin.tie(0);
#define MOD (ll)(1e9+7)
#define INF (ll)(1e18)
#define debug(...) fprintf(stderr, __VA_ARGS__),fflush(stderr)
#define time__(d) for(long blockTime = 0; (blockTime == 0 ? (blockTime=clock()) != 0 : false);\
debug("%s time : %.4fs\n", d, (double)(clock() - blockTime) / CLOCKS_PER_SEC))
typedef long long int ll;
typedef long double ld;
typedef pair<ll,ll> PII;
typedef pair<int,int> pii;
typedef vector<vector<int>> vii;
typedef vector<vector<ll>> VII;
ll gcd(ll a,ll b){if(!b)return a;else return gcd(b,a%b);}
const int MAXN = 1e5+2;
vector<vector<pii>> adj(MAXN);
vector<ll>udist(MAXN,INF),vdist(MAXN,INF),sdist(MAXN,INF),tdist(MAXN,INF);
vector<bool>vis(MAXN,0);
vii tadj(MAXN);
void djikstra(int s,vector<ll>&dist){
	priority_queue<PII,vector<PII>,greater<PII>>pq;
	pq.push({0,s});
	dist[s] = 0;
	while(!pq.empty()){
		ll d = pq.top().fi;
		int v = pq.top().se;
		pq.pop();
		if(d != dist[v])continue;
		for(auto x:adj[v]){
			int to = x.fi;
			ll w = x.se;
			if(dist[to] > d+w){
				dist[to] = d+w;
				pq.push({d+w,to});
			}
		}
	}
}
vector<ll>topo;
void dfs(int v){
	vis[v] = 1;
	for(int x:tadj[v]){
		if(!vis[x]){
			dfs(x);
		}
	}
	topo.pb(v);
}
int main()
{
  owo
	int n,m;
	cin>>n>>m;
	int s,t,u,v;
	cin>>s>>t>>u>>v;
	for(int i=0;i<m;i++){
		ll a,b,c;
		cin>>a>>b>>c;
		adj[a].pb({b,c});
		adj[b].pb({a,c});
	}
	djikstra(u,udist);
	djikstra(v,vdist);
	djikstra(s,sdist);
	djikstra(t,tdist);
	queue<int>q;
	q.push(s);
	vis[s] = 1;
	while(!q.empty()){
		int v = q.front();
		q.pop();
		for(auto x:adj[v]){
			int to = x.fi;
			ll w = x.se;
			if(sdist[v]+w + tdist[to] == sdist[t]){
				tadj[v].pb(to);
				if(!vis[to])q.push(to);
				vis[to] = 1;
			}
		}
		
	}
	for(int i=1;i<=n;i++)vis[i] = 0;
	dfs(s);
	ll ans = vdist[u];
	vector<ll>dp(n+1,INF);
	/*
	for(int i=1;i<=n;i++){
		cout<<i<<":";
		for(int x:tadj[i])cout<<x<<" ";
		cout<<'\n';
	}*/
	for(ll z:topo){
		dp[z] = vdist[z];
		for(int x:tadj[z]){
			dp[z] = min(dp[x],dp[z]);
		}
		ans = min(ans,dp[z]+udist[z]);
	}
	for(int i=1;i<=n;i++)dp[i] = INF;
	for(ll z:topo){
		dp[z] = udist[z];
		for(int x:tadj[z]){
			dp[z] = min(dp[x],dp[z]);
		}
		ans = min(ans,dp[z]+vdist[z]);
	}
	cout<<ans<<'\n';
}

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