Submission #227593

#	Time	Username	Problem	Language	Result	Execution time	Memory
227593		bensonlzl	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	470 ms	27312 KiB

commuter_pass

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll,ll> pl;

ll N, M, X, Y, S, T, U, V, C, mini = 1e18;


ll distS[100005], distT[100005], distU[100005], distV[100005], dp[100005];
int visit[100005];
vector<pl> AdjList[100005];
vector<int> dpList[100005];


void dijkstra(int x, ll d[]){
	priority_queue<pl,vector<pl>,greater<pl> > pq;
	for (int i = 1; i <= N; ++i) d[i] = 1e16;
 	d[x] = 0;
 	pq.push(pl(0,x));
 	while (!pq.empty()){
 		pl t = pq.top();
 		pq.pop();
 		ll dt = t.first, v = t.second;
 		if (d[v] != dt) continue;
 		for (auto it : AdjList[v]){
 			if (d[it.first] > d[v] + it.second){
 				d[it.first] = d[v] + it.second;
 				pq.push(pl(d[it.first],it.first));
 			}
 		}
 	}
}

void dfs(int x){
	visit[x] = 1;
	for (auto it : dpList[x]){
		if (!visit[it]) dfs(it);
		dp[x] = min(dp[x],dp[it]);
	}
}

void runDP(ll d1[], ll d2[]){
	for (int i = 1; i <= N; ++i){
		dp[i] = d2[i];
		visit[i] = 0;
	}
	for (int i = 1; i <= N; ++i){
		if (!visit[i]) dfs(i);
	}
	for (int i = 1; i <= N; ++i){
		mini = min(mini,dp[i] + d1[i]);
	}
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);	
	cin >> N >> M;
	cin >> S >> T;
	cin >> U >> V;
	for (int i = 1; i <= M; ++i){
		cin >> X >> Y >> C;
		AdjList[X].push_back(pl(Y,C));
		AdjList[Y].push_back(pl(X,C));
	}
	dijkstra(S,distS); dijkstra(T,distT); dijkstra(U,distU); dijkstra(V,distV);
	for (int i = 1; i <= N; ++i){
		for (auto it : AdjList[i]){
			if (distS[i] + it.second + distT[it.first] == distS[T]){
				dpList[i].push_back(it.first);
			}
		}
	}
	runDP(distU,distV);
	runDP(distV,distU);
	cout << mini << '\n';
}

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