Submission #1273838

#	Time	Username	Problem	Language	Result	Execution time	Memory
1273838		quanduongxuan12	Commuter Pass (JOI18_commuter_pass)	C++20	15 / 100	2094 ms	29036 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;
#define name "commuter"
#define MAXN 200005
#define pb push_back
#define pf push_front
#define ll long long
#define ii pair<int, int>
#define fs first
#define sc second
#define ill pair<int, ll>
#define lli pair<ll, int>
#define llll pair<ll, ll>
#define all(v) v.begin(),v.end()
#define uni(v) v.erase(unique(all(v)),v.end())
#define bit(n,i) (((n)>>(i))&1)
#define FOR(i,a,b) for (int i=(a),_b=(b); i<=_b; i++)
#define FORD(i,a,b) for (int i=(a),_b=(b); i>=_b; i--)
#define MASK(i) (1LL<<(i))
const ll INF=1e18;
const int MOD=1e9+7;
void add(int &u, int v){
    u+=v;
    if (u>=MOD) u-=MOD;
}
void sub(int &u, int v){
    u-=v;
    if (u<0) u+=MOD;
}
void minimize(ll &u, ll v){
    u=min(u,v);
}
void maximize(int &u, int v){
    u=max(u,v);
}
long long Rand(long long l, long long r){
    ll tmp=0;
    FOR(i,1,4) tmp=((tmp<<15)^(((1<<15)-1)&rand()));
    return l+tmp%(r-l+1);
}
int n,m;
vector<ii> adj[MAXN];
vector<int> child[MAXN],par[MAXN];
int S,T,U,V;
ll d[3][MAXN];
priority_queue<lli,vector<lli>,greater<lli>> pq;
void dijkstra(int type, int s){
    FOR(i,1,n) d[type][i]=INF;
    d[type][s]=0;
    pq.push({0,s});
    while (pq.size()){
        ii tmp=pq.top();
        pq.pop();
        ll w=tmp.fs;
        int u=tmp.sc;
        if (w>d[type][u]) continue;
        for (ii pairs:adj[u]){
            int v=pairs.fs;
            int wei=pairs.sc;
            if (d[type][v]>=d[type][u]+1LL*wei){
                if (type==0){
                    if (d[type][v]>d[type][u]+1LL*wei){
                        par[v].clear();
                    }
                    par[v].pb(u);
                }
                if (d[type][v]>d[type][u]+1LL*wei){
                    d[type][v]=d[type][u]+1LL*wei;
                    pq.push({d[type][v],v});
                }
            }
        }
    }
}
ll ans;
ll f[MAXN],g[MAXN];
void dfs(int type, int u){
    if (type==1){
        for (int v:child[u]){
            f[v]=min(f[u],d[1][v]);
            dfs(type,v);
        }
    }
    else{
        for (int v:par[u]){
            g[v]=min(g[u],d[2][v]);
            dfs(type,v);
        }
    }
}
bool visited[MAXN];
int main()
{
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    /*
    srand(time(0));
    n=Rand(100000,100000);
    m=Rand(200000,200000);
    S=Rand(1,n);
    T=Rand(1,n);
    U=Rand(1,n);
    V=Rand(1,n);
    cout<<n<<" "<<m<<"\n";
    cout<<S<<" "<<T<<"\n";
    cout<<U<<" "<<V<<"\n";
    */
    cin>>n>>m;
    cin>>S>>T;
    cin>>U>>V;
    FOR(i,1,m){
        int x,y,w;
        /*
        x=Rand(1,n);
        y=Rand(1,n);
        w=Rand(1,(int)1e9);
        cout<<x<<" "<<y<<" "<<w<<"\n";
        */
        cin>>x>>y>>w;
        adj[x].pb({y,w});
        adj[y].pb({x,w});
    }
    dijkstra(0,S);
    dijkstra(1,U);
    dijkstra(2,V);
    queue<int> Q;
    Q.push(T);
    visited[T]=1;
    while (Q.size()){
        int u=Q.front();
        Q.pop();
        for (int p:par[u]){
            child[p].pb(u);
            if (!visited[p]){
                visited[p]=1;
                Q.push(p);
            }
        }
    }
    ll ans=d[1][V];
    memset(f,0x3f,sizeof(f));
    memset(g,0x3f,sizeof(g));
    f[S]=d[1][S];
    g[T]=d[2][T];
    dfs(1,S);
    dfs(2,T);
    FOR(i,1,n) minimize(ans,f[i]+g[i]);
    ///
    memset(f,0x3f,sizeof(f));
    memset(g,0x3f,sizeof(g));
    swap(S,T);
    FOR(i,1,n) swap(par[i],child[i]);
    f[S]=d[1][S];
    g[T]=d[2][T];
    dfs(1,S);
    dfs(2,T);
    FOR(i,1,n) minimize(ans,f[i]+g[i]);
    cout<<ans;
    return 0;
}

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