Submission #415878

#	Time	Username	Problem	Language	Result	Execution time	Memory
415878		Emin2004	Dreaming (IOI13_dreaming)	C++14	100 / 100	149 ms	20076 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define pb push_back
#define pii pair<int, ll>
#define F first
#define S second

const int N = 100005;

int used[N];
ll dis[N], dis1[N], dis2[N];
vector <pii> v[N];
vector <int> vis;

void DFS(int node){
    used[node] = 1;
    vis.pb(node);
    for(pii i : v[node]){
        if(used[i.F] == 0){
            dis[i.F] = dis[node] + i.S;
            DFS(i.F);
        }
    }
}

void DFS1(int node){
    used[node] = 2;
    for(pii i : v[node]){
        if(used[i.F] != 2){
            dis1[i.F] = dis1[node] + i.S;
            DFS1(i.F);
        }
    }
}

void DFS2(int node){
    used[node] = 3;
    for(pii i : v[node]){
        if(used[i.F] != 3){
            dis2[i.F] = dis2[node] + i.S;
            DFS2(i.F);
        }
    }
}

int travelTime(int n, int m, int l, int a[], int b[], int t[]) {
    if(n == 1) return 0;
    for(int i = 0; i < m; i++){
        v[a[i]].pb({b[i], t[i] * 1ll});
        v[b[i]].pb({a[i], t[i] * 1ll});
    }
    vector<ll> results;
    ll ans = 0;
    for(int i = 0; i < n; i++){
        if(!used[i]) {
            vis.clear();
            ll mx = 0, dd = i;
            DFS(dd);
            for(int j : vis){
                if(dis[j] >= mx) {
                    mx = dis[j];
                    dd = j;
                }
                dis[j] = 0;
            }

            DFS1(dd);
            mx = 0;
            for(int j : vis){
                if(dis1[j] >= mx) {
                    mx = dis1[j];
                    dd = j;
                }
            }

            dis[dd] = 0;
            DFS2(dd);
            ll res = mx;
            for(int j : vis){
                res = min(res, max(dis1[j], dis2[j]));
            }
            results.pb(res);
            ans = max(ans, mx);
        }
    }
    sort(results.begin(), results.end());
    int sz = results.size();
    ans = max(ans, results[sz - 1]);
    if(sz >= 2) ans = max(ans, results[sz - 2] + l + results[sz - 1]);
    if(sz >= 3) ans = max(ans, results[sz - 2] + results[sz - 3] + l + l);
    return ans;
}

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 18 / 18
• Subtask 5: 12 / 12
• Subtask 6: 23 / 23