Submission #459650

#	Time	Username	Problem	Language	Result	Execution time	Memory
459650		nickmet2004	Aesthetic (NOI20_aesthetic)	C++11	100 / 100	918 ms	84944 KiB

Aesthetic

#include<bits/stdc++.h>
#define ll long long
using namespace std;
vector<pair<ll, pair<ll, ll > > > v[300009];
vector<ll> T[300009],W[300009];
ll d1[300009],dn[300009], f[300009], g[300009],ea[300009],eb[300009],ec[300009], par[300009],path[300009],wh[300009];
multiset<pair<ll,ll> > S;
void ad(ll x){
    g[x] = 1;
    for(auto E : v[x]){
        ll y = E.first, l = E.second.first,  u= E.second.second;
        auto it= S.find({dn[y] + l + d1[x], u});
        if(g[y] == 1) S.erase(it);
        if(g[y] == 0) S.insert({dn[x] + l + d1[y], u});
    }
}
void dfs(int x, int p){
    if(path[x]) wh[x] = x;
    else wh[x] = wh[p];
    T[wh[x]].push_back(x);
    for(int y : W[x]){
        dfs(y, x);
    }
}
ll A = 0;
main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    ll n, m;
    cin >> n >> m;
    for(ll i = 0; i < m; i++){
        cin>>ea[i]>>eb[i]>>ec[i];
    }
    for(ll i = m-1; i >= 0; i--){
        ll a = ea[i], b = eb[i], c = ec[i];
        if(a != b){
            v[a].push_back({b, {c,A}});
            v[b].push_back({a, {c,A}});
        }
        A = max(A, c);
    }
    for(ll i = 1; i <= n; i++){
        d1[i] = 1e18;
        dn[i] = 1e18;
    }
    d1[1] = 0;
    dn[n] = 0;
    priority_queue<pair<ll, ll> > q;
    q.push({0, 1});
    while(q.size()){
        ll x = q.top().second;
        q.pop();
        if(f[x]) continue;
        f[x] = 1;
        for(auto E: v[x]){
            ll y = E.first, l = E.second.first;
            if(!f[y] && d1[y] > d1[x] + l){
                d1[y] = d1[x] + l;
                par[y] = x;
                q.push({-d1[y], y});
            }
        }
    }
    q.push({0, n});
    for(ll i = 1; i <= n; i++)
        f[i] = 0;
    while(q.size()){
        ll x = q.top().second;
        q.pop();
        if(f[x]) continue;
        f[x] = 1;
        for(auto E: v[x]){
            ll y = E.first, l = E.second.first;
            if(!f[y] && dn[y] > dn[x] + l){
                dn[y] = dn[x] + l;
                q.push({-dn[y], y});
            }
        }
    }
    ll ans = d1[n];
    ll X = n;
    while(1){
        path[X] = 1;
        if(X == 1) break;
        X = par[X];
    }
 
    for(ll i = 1; i <= n; i++){
        W[par[i]].push_back(i);
    }
    dfs(1,0);
    ll x = n;
    while(1){
        for(ll y : T[x])
            ad(y);
        if(x == 1) break;
        x = par[x];
        if(S.size() == 0) continue;
        ll U = S.begin()->first + S.begin()->second;
        auto it = S.begin();
        it++;
        if(it != S.end()) U = min(U, it->first);
        ans = max(ans,   U);
    }
    cout<<ans<<endl;
}

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: 27 / 27