Submission #945934

#	Time	Username	Problem	Language	Result	Execution time	Memory
945934		ezzzay	Commuter Pass (JOI18_commuter_pass)	C++14	55 / 100	313 ms	34800 KiB

commuter_pass

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define ff first
#define ss second
#define pb push_back
const int N=3e5+5;
vector<pair<int,int>>v[N];
int n,m,s,t,x,y;
int dist[N];
int tmp[N];
int par[N];
int d[500][500];
bool vis[N];
vector<pair<int,int>>vc;
void dfs(int a){
    vis[a]=1;
    for(auto p:v[a]){
        int b=p.ff;
        int c=p.ss;
        if(vis[b]==0 and dist[b]+c==dist[a])dfs(b);
    }
}
void sbtsk1(){
    for(int i=0;i<m;i++){
        int a,b,c;
        cin>>a>>b>>c;
        v[a].pb({b,c});
        v[b].pb({a,c});
    }
    for(int i=1;i<=n;i++){
        dist[i]=1e16;
    }
    priority_queue<pair<int,int>>q;
    q.push({0,s});
    par[s]=s;
    dist[s]=0;
    vis[s]=1;
    while(!q.empty()){
        int w=-q.top().ff;
        int a=q.top().ss;
        q.pop();
        if(dist[a]<w)continue;
        for(auto p:v[a]){
            
            int b=p.ff;
            int c=p.ss;
            if(dist[a]+c<dist[b]){
               
                dist[b]=dist[a]+c;
                par[b]=a;
                q.push({-dist[b],b});
            }
        }
    }
    
    dfs(t);
    for(int i=1;i<=n;i++){
        dist[i]=1e16;
    }
    s=y;
    q.push({0,s});
    dist[s]=0;
    while(!q.empty()){
        int w=-q.top().ff;
        int a=q.top().ss;
        q.pop();
        if(dist[a]<w)continue;
        for(auto p:v[a]){
            int b=p.ff;
            int c=p.ss;
            if(dist[a]+c<dist[b]){
                dist[b]=dist[a]+c;
                par[b]=a;
                q.push({-dist[b],b});
            }
        }
    }
    int ans=1e16;
    for(int i=1;i<=n;i++){
        if(vis[i]){
           
            ans=min(ans,dist[i]);
        }
    }
    cout<<ans;
}
void sbtsk2(){
    for(int i=0;i<m;i++){
        int a,b,c;
        cin>>a>>b>>c;
        v[a].pb({b,c});
        v[b].pb({a,c});
    }
    for(int i=1;i<=n;i++){
        dist[i]=1e16;
    }
    priority_queue<pair<int,int>>q;
    q.push({0,s});
    par[s]=s;
    dist[s]=0;
    while(!q.empty()){
        int w=-q.top().ff;
        int a=q.top().ss;
        q.pop();
        if(dist[a]<w)continue;
        for(auto p:v[a]){
            int b=p.ff;
            int c=p.ss;
            if(dist[a]+c<dist[b]){
                dist[b]=dist[a]+c;
                par[b]=a;
                q.push({-dist[b],b});
            }
        }
    }
    while(t!=s){
        v[t].pb({par[t],0});
        v[par[t]].pb({t,0});
        t=par[t];
    }
    for(int i=1;i<=n;i++){
        dist[i]=1e16;
    }
    s=x;
    q.push({0,s});
    par[s]=s;
    dist[s]=0;
    while(!q.empty()){
        int w=-q.top().ff;
        int a=q.top().ss;
        q.pop();
        if(dist[a]<w)continue;
        for(auto p:v[a]){
            int b=p.ff;
            int c=p.ss;
            if(dist[a]+c<dist[b]){
                dist[b]=dist[a]+c;
                par[b]=a;
                q.push({-dist[b],b});
            }
        }
    }
    cout<<dist[y];
}
void subtsk3(){
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(i==j){
                d[i][j]=0;
                continue;
            }
            d[i][j]=1e14;
        }
    }
    for(int i=0;i<m;i++){
        int a,b,c;
        cin>>a>>b>>c;
        d[a][b]=min(d[a][b],c);
        d[b][a]=min(d[b][a],c);
    }
    for(int k=1;k<=n;k++){
        for(int i=1;i<=n;i++){
            for(int j=1;j<=n;j++){
                if(d[i][j]> d[i][k]+d[k][j]){
                    d[i][j]=d[i][k]+d[k][j];
                }
            }
        }
    }
    
    int ans=d[x][y];
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(d[s][i]+d[i][j]+d[j][t]==d[s][t]){
                
                ans=min(ans,d[x][i]+d[j][y]);
                ans=min(ans,d[x][j]+d[i][y]);
                
            }
            
        }
    }
    cout<<ans;
}
signed main(){
    cin>>n>>m>>s>>t>>x>>y;
     if(n<=300){
        subtsk3();
        return 0;
    }
    if(s==x){
        sbtsk1();
        return 0;
    }
   
    sbtsk2();
}

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