Submission #540719

#	Time	Username	Problem	Language	Result	Execution time	Memory
540719		browntoad	Commuter Pass (JOI18_commuter_pass)	C++14	100 / 100	577 ms	39416 KiB

commuter_pass

#include <bits/stdc++.h>
#pragma GCC optimize ("Ofast", "unroll-loops")
using namespace std;
#define ll long long
#define int ll
#define FOR(i,a,b) for (int i = (a); i<(b); i++)
#define REP(i,n) FOR(i,0,n)
#define REP1(i,n) FOR(i,1,n+1)
#define RREP(i,n) for (int i=(n)-1; i>=0; i--)
#define RREP1(i,n) for (int i=(n); i>=1; i--)
#define f first
#define s second
#define pb push_back
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)(x.size())
#define SQ(x) (x)*(x)
#define pii pair<int, int>
#define pdd pair<double ,double>
#define pcc pair<char, char> 
#define endl '\n'
//#define TOAD
#ifdef TOAD
#define bug(x) cerr<<__LINE__<<": "<<#x<<" is "<<x<<endl
#define IOS()
#else
#define bug(...)
#define IOS() ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#endif
 
const ll inf = 1ll<<60;
const int iinf=2147483647;
const ll mod = 1e9+7;
const ll maxn=1e5+5;
const double PI=acos(-1);
 
ll pw(ll x, ll p, ll m=mod){
    ll ret=1;
    while (p>0){
        if (p&1){
            ret*=x;
            ret%=m;
        }
        x*=x;
        x%=m;
        p>>=1;
    }
    return ret;
}
 
ll inv(ll a, ll m=mod){
    return pw(a,m-2);
}
 
//=======================================================================================
int n, m, s, t, u, v;
struct edge{
    int st, en;
    int w;
};
vector<edge> ing[maxn];
vector<int> graph[maxn];
vector<edge> E(2*maxn);
vector<int> dis(maxn), rdis(maxn), dis3(maxn), dis4(maxn);
vector<bool> ds1(maxn), ds2(maxn), ds3(maxn), ds4(maxn), seen(maxn);
vector<int> indeg(maxn);
void dij1(){
    priority_queue<pii, vector<pii>, greater<pii> > pq;
    pq.push({0, s});
    //dis[s]=0;
    //ds1[s]=1;
    while(pq.size()){
        pii x=pq.top(); pq.pop();
        if (ds1[x.s]) continue;
        ds1[x.s]=1;
        dis[x.s]=x.f;
        REP(i,SZ(ing[x.s])){
            pq.push({x.f+ing[x.s][i].w, ing[x.s][i].en});
        }
    }
}
void dij2(){
    priority_queue<pii, vector<pii>, greater<pii> > pq;
    pq.push({0, t});
    //rdis[t]=0;
    //ds2[t]=1;
    while(pq.size()){
        pii x=pq.top(); pq.pop();
        if (ds2[x.s]) continue;
        ds2[x.s]=1;
        rdis[x.s]=x.f;
        REP(i,SZ(ing[x.s])){
            pq.push({x.f+ing[x.s][i].w, ing[x.s][i].en});
        }
    }
}
void dij3(){
    priority_queue<pii, vector<pii>, greater<pii> > pq;
    pq.push({0, u});
    //ds3[u]=1;
    while(pq.size()){
        pii x=pq.top(); pq.pop();
        if (ds3[x.s]) continue;
        ds3[x.s]=1;
        dis3[x.s]=x.f;
        REP(i,SZ(ing[x.s])){
            pq.push({x.f+ing[x.s][i].w, ing[x.s][i].en});
        }
    }
}
void dij4(){
    priority_queue<pii, vector<pii>, greater<pii> > pq;
    pq.push({0, v});
    //ds3[u]=1;
    while(pq.size()){
        pii x=pq.top(); pq.pop();
        if (ds4[x.s]) continue;
        ds4[x.s]=1;
        dis4[x.s]=x.f;
        REP(i,SZ(ing[x.s])){
            pq.push({x.f+ing[x.s][i].w, ing[x.s][i].en});
        }
    }
}
signed main (){
    IOS();
    cin>>n>>m>>s>>t>>u>>v;
    REP(i,m){
        cin>>E[i].st>>E[i].en>>E[i].w;
        ing[E[i].st].pb({E[i].st, E[i].en, E[i].w});
        ing[E[i].en].pb({E[i].en, E[i].st, E[i].w});
    }
    dij1();
    dij2();
    dij3();
    dij4();
    REP(i,m){
        if (dis[E[i].st]+rdis[E[i].en]+E[i].w==dis[t]){
            graph[E[i].st].pb(E[i].en);
            indeg[E[i].en]++;
        }
        if (dis[E[i].en]+rdis[E[i].st]+E[i].w==dis[t]){
            graph[E[i].en].pb(E[i].st);
            indeg[E[i].st]++;
        }
    }
    int ans=dis3[v];
    queue<int> qu;
    vector<pii> dp(n+1);
    REP1(i,n){
        if (indeg[i]==0) {
            qu.push(i);
            seen[i]=1;
        }
        dp[i].f=dis3[i];
        dp[i].s=dis4[i];
    }
    while(qu.size()){
        int x=qu.front(); qu.pop();
        ans=min({ans, dp[x].f+dis4[x], dp[x].s+dis3[x]});
        REP(i,SZ(graph[x])){
            if (seen[graph[x][i]]) continue;
            indeg[graph[x][i]]--;
            dp[graph[x][i]].f=min(dp[graph[x][i]].f, dp[x].f);
            dp[graph[x][i]].s=min(dp[graph[x][i]].s, dp[x].s);
            if (indeg[graph[x][i]]==0){
                qu.push(graph[x][i]);
                seen[graph[x][i]]=1;
            }
        }
    }
    cout<<ans<<endl;
}
/*
8 9
1 5
2 6
1 2 5
2 3 5
3 4 5
4 5 15
5 6 5
6 7 5
7 8 5
8 1 15
4 8 1
*/

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