Submission #748553

#	Time	Username	Problem	Language	Result	Execution time	Memory
748553		Pacybwoah	Olympic Bus (JOI20_ho_t4)	C++14	100 / 100	799 ms	7084 KiB

ho_t4

#pragma GCC optimize("O3","unroll-loops","Ofast")
#include<iostream>
#include<vector>
#include<queue>
#include<set>
#define ll long long
using namespace std;
int n,m;
vector<bool> crit;
vector<pair<pair<int,int>,pair<ll,ll>>> edges;
void dijk(vector<vector<pair<pair<int,int>,pair<ll,ll>>>> &g,vector<ll> &dist,int s,int skip,bool flag){
    dist[s]=0;
    priority_queue<pair<int,ll>,vector<pair<int,ll>>,greater<pair<int,ll>>> pq;
    vector<int> pre(n+1);
    pq.push(make_pair(0,s));
    while(!pq.empty()){
        auto node=pq.top();
        pq.pop();
        if(dist[node.second]<node.first) continue;
        for(auto x:g[node.second]){
            if(x.first.second==skip) continue;
            if(dist[x.first.first]>dist[node.second]+x.second.first){
                if(flag) pre[x.first.first]=x.first.second;
                dist[x.first.first]=dist[node.second]+x.second.first;
                pq.push(make_pair(dist[x.first.first],x.first.first));
            }
        }
        if(skip!=-1&&edges[skip].first.second==node.second){
            if(dist[edges[skip].first.first]>dist[node.second]+edges[skip].second.first){
                dist[edges[skip].first.first]=dist[node.second]+edges[skip].second.first;
                pq.push(make_pair(dist[edges[skip].first.first],edges[skip].first.first));
            }
        }
    }
    if(flag){
        for(int i=1;i<=n;i++){
            if(i==s) continue;
            crit[pre[i]]=1;
        }
    }
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll a,b,c,d;
    cin>>n>>m;
    crit.resize(m);
    vector<vector<pair<pair<int,int>,pair<ll,ll>>>> graph(n+1),hparg(n+1);
    for(int i=0;i<m;i++){
        cin>>a>>b>>c>>d;
        edges.push_back(make_pair(make_pair(a,b),make_pair(c,d)));
        graph[a].push_back(make_pair(make_pair(b,i),make_pair(c,d)));
        hparg[b].push_back(make_pair(make_pair(a,i),make_pair(c,d)));
    }
    vector<ll> from1(n+1,1e18),fromn(n+1,1e18),to1(n+1,1e18),ton(n+1,1e18);
    dijk(graph,from1,1,-1,1);
    dijk(graph,fromn,n,-1,1);
    dijk(hparg,to1,1,-1,1);
    dijk(hparg,ton,n,-1,1);
    ll ans=from1[n]+fromn[1];
    for(int i=0;i<m;i++){
        if(crit[i]){
            vector<ll> tmp1(n+1,1e18),tmp2(n+1,1e18);
            dijk(graph,tmp1,1,i,0);
            dijk(graph,tmp2,n,i,0);
            ans=min(ans,tmp1[n]+tmp2[1]+edges[i].second.second);
        }
        else{
            ans=min(ans,min(from1[n],from1[edges[i].first.second]+edges[i].second.first+ton[edges[i].first.first])+min(fromn[1],fromn[edges[i].first.second]+edges[i].second.first+to1[edges[i].first.first])+edges[i].second.second);
        }
    }
    if(ans>=1e18) cout<<-1;
    else cout<<ans;
}

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