Submission #487098

#	Time	Username	Problem	Language	Result	Execution time	Memory
487098		PoPularPlusPlus	Commuter Pass (JOI18_commuter_pass)	C++17	100 / 100	262 ms	24424 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long 
#define pb(e) push_back(e)
#define sv(a) sort(a.begin(),a.end())
#define sa(a,n) sort(a,a+n)
#define mp(a,b) make_pair(a,b)
#define vf first
#define vs second
#define ar array
#define all(x) x.begin(),x.end()
const int inf = 0x3f3f3f3f;
const int mod = 1000000007; 
const double PI=3.14159265358979323846264338327950288419716939937510582097494459230;
bool remender(ll a , ll b){return a%b;}

const int N = 100002;
vector<pair<int,ll>> adj[N];
ll dis[N];

void mem(){
	for(int i = 0; i < N; i++)dis[i] = 1e18;
}

void Dijkstra(ll e){
	 priority_queue< pair<ll,ll>, vector <pair<ll,ll>> , greater<pair<ll,ll>> > pq; 
	 dis[e]=0;
	 pq.push({0,e});
	 while(!pq.empty()){
		 ll node = pq.top().second,ww=pq.top().first;
		 pq.pop();
		 if(dis[node] < ww)continue;
		 for(auto i : adj[node]){
			 ll w = i.second;
			 if(dis[i.first] > dis[node] + w){
				 dis[i.first] = dis[node] + w;
				 pq.push({dis[i.first],i.first});
			 }
		 }
	 }
}

void solve(){
	int n , m;
	cin >> n >> m;
	int s , t;
	cin >> s >> t;
	int a , b;
	cin >> a >> b;
	for(int i = 0; i < m; i++){
		ll x , y , z;
		cin >> x >> y >> z;
		adj[x].pb(mp(y,z));
		adj[y].pb(mp(x,z));
	}
	ll dis1[N] , dis2[N];
	mem();
	Dijkstra(a);
	for(int i = 0; i <= n; i++)dis1[i] = dis[i];
	mem();
	Dijkstra(b);
	for(int i = 0; i <= n; i++)dis2[i] = dis[i];
	mem();
	Dijkstra(s);
	ll mn[N] , mx[N];
	for(int i = 0; i <= n; i++)mn[i] = dis1[i];
	for(int i = 0; i <= n; i++)mx[i] = dis2[i];
	queue<int> q;
	bool vis[N];
	memset(vis,0,sizeof vis);
	vis[t] = 1;
	q.push(t);
	int cnt[N];
	memset(cnt,0,sizeof cnt);
	while(q.size()){
		int node = q.front();
		q.pop();
		for(auto i : adj[node]){
			if(dis[i.vf] + i.vs == dis[node]){
				cnt[i.vf]++;
				if(!vis[i.vf]){
					vis[i.vf] = 1;
					q.push(i.vf);
				}
			}
		}
	}
	ll ans = dis1[b];
	q.push(t);
	while(q.size()){
		int node = q.front();
		q.pop();
		ans = min(ans , min(dis1[node] + mx[node] , dis2[node] + mn[node]));
		for(auto i : adj[node]){
			if(dis[i.vf] == dis[node] - i.vs){
				mn[i.vf] = min(mn[i.vf] , mn[node]);
				mx[i.vf] = min(mx[i.vf] , mx[node]);
				cnt[i.vf]--;
				if(cnt[i.vf] == 0){
					q.push(i.vf);
				}
			}
		}
	}
	cout << ans << '\n';
}

int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
	//int t;cin >> t;while(t--)
	solve();
	return 0;
}

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