Submission #1086838

#	Time	Username	Problem	Language	Result	Execution time	Memory
1086838		peacebringer1667	Commuter Pass (JOI18_commuter_pass)	C++17	16 / 100	219 ms	21420 KiB

commuter_pass

#include<bits/stdc++.h>
#define ll long long
#define ldb long double
#define fi first
#define se second
#define sza(a) (int)a.size()
#define pir pair<int,int>
#define pirll pair<ll,int>
using namespace std;
const int maxn = 1e5 + 5;

ll dist[maxn][2],dp[maxn],D[maxn][2];
bool mark[maxn];
vector <vector<pir>> vec(maxn);

void input(int n,int m){
	while (m--){
		int u,v,w;
		cin >> u >> v >> w;
		vec[u].push_back({v,w});
		vec[v].push_back({u,w});
	}
}

void dijkstra(int source,int n,int st){
	for (int i = 1 ; i <= n ; i++) mark[i] = 0;
	priority_queue <pirll,vector<pirll>,greater<pirll>> pq;
	pq.push({0,source});
	
	while (pq.size()){
		pirll t = pq.top();
		pq.pop();
		
		int u = t.se;ll w = t.fi;
		if (mark[u]) continue;
		mark[u] = 1;
		dist[u][st] = w;
		
		for (pir v : vec[u])
		  if (!mark[v.fi])
		    pq.push({v.se + w,v.fi});
	}
}


vector <int> traverse_order;

void sol(int source,int n,int st){
	for (int i = 1 ; i <= n ; i++) mark[i] = 0;
	priority_queue <pirll,vector<pirll>,greater<pirll>> pq;
	pq.push({0,source});
	
	while (pq.size()){
		pirll t = pq.top();
		pq.pop();
		
		int u = t.se;ll w = t.fi;
		if (mark[u]) continue;
		mark[u] = 1;
		D[u][st] = w;
		if (!st)
		  traverse_order.push_back(u);
		
		for (pir v : vec[u])
		  if (!mark[v.fi])
		    pq.push({v.se + w,v.fi});
	}
}

ll solve(int n,int T,int U,int V){
	ll inf = 1e18;
	for (int i = 1 ; i <= n ; i++) dp[i] = inf;
	ll res = dist[V][0];
	
	for (int u : traverse_order)
	  if (D[u][0] + D[u][1] == D[T][0]){
		dp[u] = min(dp[u],dist[u][0]);
		ll tmp = inf;
		
		for (pir node : vec[u]){
			int v = node.fi,w = node.se;
			
			if (D[v][0] + w == D[u][0]){
			  tmp = min(tmp,dp[v] + dist[u][1]);
		      dp[u] = min(dp[u],dp[v]);
		   }
		}
		
		res = min(res,tmp);
	}
	
	return res;
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);cout.tie(0);
	
	int n,m,S,T,U,V;
	cin >> n >> m >> S >> T >> U >> V;
	input(n,m);
	dijkstra(U,n,0);
	dijkstra(V,n,1);
	
	sol(S,n,0);
	sol(T,n,1);
	
	cout << solve(n,T,U,V); 		

	return 0;
}

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