제출 #293259

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
293259		crossing0ver	Aesthetic (NOI20_aesthetic)	C++17	0 / 100	6 ms	5248 KiB

Aesthetic

#include<bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
#define pii pair<int,int>
#define ll long long
#define pb push_back
#define vi vector<int>
#define se second
#define fi first
using namespace std;
const int N = 1e5+5;
vector<pii> adj[N];
int n,m;
int A[N],B[N],W[N],NUM[N][2],MX[N],par[N],good[N],sub[N],id[N];
ll D[N],FROM_N[N];
set<pii> path;
void dijkstra(int s) {
    priority_queue<pair<ll,int>,vector<pair<ll,int> >,greater<pair<ll,int> > > pq;
        pq.push({0,s});
        vector<bool> vis(n+1);
        vector<ll> d(n+1);
        for (int i = 1; i <= n; i++)
            d[i] = 10000000000000000;
        d[s] = 0;
        par[s] = 0;
        id[s] = 0;
        while(!pq.empty()) {
            auto i1 = pq.top();
            pq.pop();
            int v = i1.se;
            if (vis[v]) continue;
            ll dis = i1.fi;
            vis[v] = 1;
            for (auto i : adj[v])
                if (!vis[i.fi] && d[i.fi] > dis + i.se) {
                    d[i.fi] = dis + i.se;
                    id[i.fi] = id[v] + 1;
                    par[i.fi] = v;
                    pq.push({d[i.fi],i.fi});
                }
        }
        if (s == n)
        for (int i = 1; i <= n; i++)
            FROM_N[i] = d[i];
        else {
                for (int i = 2; i <= n; i++) {
                    path.insert({i,par[i]});
                    path.insert({par[i],i});
                }
                for (int i = 1; i <= n; i++)
                    D[i] = d[i];
               int j = n;
                good[1] = 1;
            while(j != 1) {
                good[j] = 1;
                j = par[j];
            }
            vector<pair<ll,int> > g;
            for (int i =1 ; i <= n; i++) {
                g.pb({d[i],i});
            }
        sort(all(g));
        for (auto i1 : g) {
            int v = i1.se;
            if (!good[v])
                sub[v] = sub [ par[v] ];
            else sub[v] = v;
        }
        }
}
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
            int a,b,w;
        cin >> a >> b >> w;
        A[i] = a, B[i] = b;
        W[i] = w;
        NUM[i][0] = adj[a].size();
        NUM[i][1] = adj[b].size();
        adj[a].pb({b,w});
        adj[b].pb({a,w});
        MX[i] = w;
    }
    dijkstra(n);
    dijkstra(1);
   // cout << FROM_N[1];exit(0);
    for (int i = m-2; i >= 0; i--)
        MX[i] = max(MX[i],MX[i+1]);
    ll ans = 0;
   // cout << D[n];exit(0);
    /*for (int i = 0; i < m; i++) {
        int a = A[i], b = B[i];
        adj[a][NUM[i][0]].se += MX[i+1];
        adj[b][NUM[i][1]].se += MX[i+1];
        // dijkstra

        priority_queue<pair<ll,int>,vector<pair<ll,int> >,greater<pair<ll,int> > > pq;
        pq.push({0,1});
        vector<bool> vis(n+1);
        vector<ll> d(n+1);
        for (int i = 1; i <= n; i++)
            d[i] = 10000000000000000;
        d[1] = 0;
        while(!pq.empty()) {
            auto i1 = pq.top();
            pq.pop();
            int v = i1.se;
            if (vis[v]) continue;
            ll dis = i1.fi;
            if (v == n) {
                ans = max(ans,dis);
                break;
            }
            vis[v] = 1;
            for (auto i : adj[v])
                if (!vis[i.fi] && d[i.fi] > dis + i.se) {
                    d[i.fi] = dis + i.se;
                    pq.push({d[i.fi],i.fi});
                }

        }
        // replace
        adj[a][NUM[i][0]].se -= MX[i+1];
        adj[b][NUM[i][1]].se -= MX[i+1];
    }*/


    for (int i = 0; i < m; i++) {
        int a = A[i], b = B[i];
        if (path.count({a,b}) == 0) continue;
        if (id[a] > id[b]) swap(a,b);
        ll C = D[n];
        C += MX[i+1];
        //adj[a][NUM[i][0]].se += MX[i+1];
        //adj[b][NUM[i][1]].se += MX[i+1];
        // dijkstra
        for (int i = 0; i < m; i++) {
            int x = A[i], y = B[i];
            if (id[sub[x]] > id[sub[y]]) swap(x,y);

            if (x == a && y == b ) continue;
            if (id[sub[x]] > id[a] || id[sub[y]] < id[b]) continue;
            C = min(C,D[x] + FROM_N[y] + W[i]);


        }
        ans = max(ans,C);


        }
        // replace
        //adj[a][NUM[i][0]].se -= MX[i+1];
        //adj[b][NUM[i][1]].se -= MX[i+1];

    cout << ans;



}

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