Submission #459642

#	Time	Username	Problem	Language	Result	Execution time	Memory
459642		nickmet2004	Aesthetic (NOI20_aesthetic)	C++11	73 / 100	841 ms	134592 KiB

Aesthetic

#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 300005;
ll n , m , au[300005] , av[300005] , aw[300005];
ll u , v , w , A;
vector<pair<ll, pair<ll , ll> > >  adj[300005];
ll d1[300005] , dn[300005] , f[300005] , par[300005] , path[300005] , son[300005];
multiset<pair<ll , ll>> S;
vector<ll> B[300005] , T[300005];
void q(ll x){
    f[x] = 1;
    for(auto y : adj[x]){
        //cout << "h";
        auto it = S.find({dn[y.first] + y.second.first + d1[x] , y.second.second});
        if(f[y.first]==1) S.erase(it);
        if(f[y.first] == 0) S.insert({dn[x] + y.second.first + d1[y.first] , y.second.second});
    }
}
void dfs(int u , int p){
    if(path[u]) son[u] = u;
    else son[u] = son[p];
    T[son[u]].emplace_back(u);
    for(int v : B[u]) dfs(v , u);
}
main (){
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> n >> m;
    for(int i  =0; i <m; ++i) cin >> au[i] >> av[i] >> aw[i];
    for(int i = m - 1; ~i; --i){
        u = au[i] , v = av[i] , w= aw[i];
        adj[u].push_back({v , {w , A}});
        adj[v].push_back({u , {w , A}});
        A = max(A , w);
        //cout << "j";
    }

    for(int i = 1; i <= n; ++i) d1[i] = dn[i] = 1e18;
    d1[1] = 0;
    dn[n] = 0;
    priority_queue<pair<ll , ll> > pq;
    pq.push({0 , 1});
    while(pq.size()){
        auto T = pq.top(); pq.pop();
        u = T.second , w = -T.first;
        if(f[u])continue;
        f[u] = 1;
        for(auto e : adj[u]){
            v = e.first;
            if(!f[v] && d1[v] > w + e.second.first){
                par[v] = u;
                d1[v] = w + e.second.first;
                pq.push({-d1[v] , v});
            }
        }
        //cout << "k";
    }
    for(int i = 1; i <= n; ++i)f[i] = 0;
    //memset(f , 0 ,sizeof(f));
    pq.push({0, n});
    while(pq.size()){
        auto T = pq.top(); pq.pop();
        u = T.second , w = -T.first;
        if(f[u])continue;
        f[u] = 1;
        for(auto e : adj[u]){
            v = e.first;
            if(!f[v] && dn[v] > w + e.second.first){
                dn[v]= w + e.second.first;
                pq.push({-dn[v] , v});
            }
        }
        //cout << "l";
    }

    ll X = n;
    while(1){
        path[X] = 1;
        if(X == 1) break;
        X = par[X];
        //cout << "n";
    }

    for(int i = 1; i <= n; ++i)B[par[i]].emplace_back(i);
    dfs(1 , 0);

    for(int i = 1; i <= n; ++i) f[i] =0;
    ll s = n;
    ll ans = d1[n];
    //cout << "ka";
    ll k;
    while(1){
        //cout << "ha";
        if(s == 1)break;
        for(ll v : T[s]) q(v);
        s = par[s];
        k = S.begin()->first + S.begin()->second;
        auto i = S.begin();
        ++i;
        if(i != S.end()) k =min(k , i->first);
        ans = max(ans , k);
    }
    cout << ans;

}

Compilation message (stderr)

Aesthetic.cpp:26:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   26 | main (){
      | ^~~~

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 7 / 7
• Subtask 4: 15 / 15
• Subtask 5: 16 / 16
• Subtask 6: 22 / 22
• Subtask 7: 0 / 27