Submission #879639

#	Time	Username	Problem	Language	Result	Execution time	Memory
879639		iskhakkutbilim	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	325 ms	24752 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#define ios ios::sync_with_stdio(false); cin.tie(NULL);cout.tie(NULL);
#define pb push_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define fr first
#define sc second
#define endl '\n'
#define int long long
#define ll long long
void fopn(string name){
	freopen((name+".in").c_str(),"r",stdin);
	freopen((name+".out").c_str(),"w",stdout);
}
const ll INF=1e18,mod=1e9+7;
const int N=1e5+5,M=1e4;
vector<pair<int,int>> g[N];
vector<int> djks(int s){
	vector<int> dist(N,INF),used(N,0);
	priority_queue<pair<int,int>> dq;
	dq.push({0,s});
	dist[s]=0;
	while(!dq.empty()){
		int a=dq.top().sc;
		dq.pop();
		if(used[a]) continue;
		used[a]=1;
		for(auto it: g[a]){
			if(dist[it.fr]>dist[a]+it.sc){
				dist[it.fr]=dist[a]+it.sc;
				dq.push({-dist[it.fr],it.fr});
			}
		}
	}
	return dist;
}
void solve(){
	int n,m;cin>>n>>m;
	int S,T,U,V;
	cin>>S>>T>>U>>V;--S,--T,--U,--V;
	for(int i=0;i<m;i++){
		int a,b,c;cin>>a>>b>>c;--a,--b;
		g[a].pb({b,c});
		g[b].pb({a,c});
	}
	vector<int> s=djks(S),t=djks(T),u=djks(U),v=djks(V);
	int ans=INF;
	vector<int> dpu(N,INF),dpv(N,INF);
	vector<pair<int,int>> vec;
	for(int i=0;i<n;i++){
		if(s[i]+t[i]==s[T])
			vec.pb({s[i],i});
	}
	sort(all(vec));
	for(auto aaa: vec){
		int i=aaa.sc;
		dpu[i]=u[i];
		dpv[i]=v[i];
		for(auto it: g[i]){
			if(t[i]+it.sc+s[it.fr]==s[T]){
				dpu[i]=min(dpu[it.fr],dpu[i]);
				dpv[i]=min(dpv[it.fr],dpv[i]);
			}
		}
		ans=min(ans,dpu[i]+v[i]);
		ans=min(ans,dpv[i]+u[i]);
	}
	//for(int i=0;i<n;i++) cout<<u[i]<<' ';
	cout<<min(ans,u[V]);
}
main(){
	//ios;
	int T=1;
	//cin>>T;
	while(T--){
		solve();
	}
}

Compilation message (stderr)

commuter_pass.cpp:72:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   72 | main(){
      | ^~~~
commuter_pass.cpp: In function 'void fopn(std::string)':
commuter_pass.cpp:13:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |  freopen((name+".in").c_str(),"r",stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:14:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 |  freopen((name+".out").c_str(),"w",stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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