Submission #927780

#	Time	Username	Problem	Language	Result	Execution time	Memory
927780		Unforgettablepl	Olympic Bus (JOI20_ho_t4)	C++17	5 / 100	52 ms	6624 KiB

ho_t4

#include <bits/stdc++.h>
using namespace std;

#define int long long

const int INF = 1e15;

struct edge{
    int u,v,c,d;
};

edge edges[50001];
set<pair<int,int>> adj[201];
vector<pair<int,int>> readj[201];
bool visited[50001];
int distFrom1[201];
int distFromN[201];
int distTo1[201];
int distToN[201];
int n;

int dijkastra(){
    priority_queue<pair<int,int>> q;
    for(bool&i:visited)i=false;
    int ans1 = INF;
    q.emplace(0,1);
    while(!q.empty()){
        auto curr = q.top();q.pop();curr.first=-curr.first;
        if(visited[curr.second])continue;
        visited[curr.second]=true;
        if(curr.second==n){ans1=curr.first;break;}
        for(auto&i:adj[curr.second]){
            if(!visited[i.first])q.emplace(-curr.first-i.second,i.first);
        }
    }
    while(!q.empty())q.pop();
    for(bool&i:visited)i=false;
    int ans2 = INF;
    q.emplace(0,n);
    while(!q.empty()){
        auto curr = q.top();q.pop();curr.first=-curr.first;
        if(visited[curr.second])continue;
        visited[curr.second]=true;
        if(curr.second==1){ans2=curr.first;break;}
        for(auto&i:adj[curr.second]){
            if(!visited[i.first])q.emplace(-curr.first-i.second,i.first);
        }
    }
    return ans1+ans2;
}

int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int m;
    cin >> n >> m;
    for(int i=1;i<=m;i++){
        int u,v,c,d;
        cin >> u >> v >> c >> d;
        edges[i] = {u,v,c,d};
        adj[u].emplace(v,c);
        readj[v].emplace_back(u,c);
    }
    for(int&i:distFrom1)i=INF;
    for(int&i:distFromN)i=INF;
    for(int&i:distTo1)i=INF;
    for(int&i:distToN)i=INF;
    priority_queue<pair<int,int>> q;
    q.emplace(0,1);
    while(!q.empty()){
        auto curr = q.top();q.pop();curr.first=-curr.first;
        if(visited[curr.second])continue;
        visited[curr.second]=true;
        distFrom1[curr.second]=curr.first;
        for(auto&i:adj[curr.second]){
            if(!visited[i.first])q.emplace(-curr.first-i.second,i.first);
        }
    }
    for(bool&i:visited)i=false;
    q.emplace(0,n);
    while(!q.empty()){
        auto curr = q.top();q.pop();curr.first=-curr.first;
        if(visited[curr.second])continue;
        visited[curr.second]=true;
        distFromN[curr.second]=curr.first;
        for(auto&i:adj[curr.second]){
            if(!visited[i.first])q.emplace(-curr.first-i.second,i.first);
        }
    }
    for(bool&i:visited)i=false;
    q.emplace(0,1);
    while(!q.empty()){
        auto curr = q.top();q.pop();curr.first=-curr.first;
        if(visited[curr.second])continue;
        visited[curr.second]=true;
        distTo1[curr.second]=curr.first;
        for(auto&i:readj[curr.second]){
            if(!visited[i.first])q.emplace(-curr.first-i.second,i.first);
        }
    }
    for(bool&i:visited)i=false;
    q.emplace(0,n);
    while(!q.empty()){
        auto curr = q.top();q.pop();curr.first=-curr.first;
        if(visited[curr.second])continue;
        visited[curr.second]=true;
        distToN[curr.second]=curr.first;
        for(auto&i:readj[curr.second]){
            if(!visited[i.first])q.emplace(-curr.first-i.second,i.first);
        }
    }
    int baseans = dijkastra();
    for(int i=1;i<=m;i++){
        int to = min(distFrom1[n],distFrom1[edges[i].v]+distToN[edges[i].u]+edges[i].c);
        int back = min(distFromN[1],distFromN[edges[i].v]+distTo1[edges[i].u]+edges[i].c);
        if(to+back+edges[i].d<baseans){
            adj[edges[i].u].erase({edges[i].v,edges[i].c});
            adj[edges[i].v].emplace(edges[i].u,edges[i].c);
            baseans = min(baseans,edges[i].d+dijkastra());
            adj[edges[i].v].erase({edges[i].u,edges[i].c});
            adj[edges[i].u].emplace(edges[i].v,edges[i].c);
        }
    }
    cout << (baseans>=INF ? -1 : baseans) << '\n';
}

• Subtask 1: 5 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 21
• Subtask 4: 0 / 63