Submission #288306

#	Time	Username	Problem	Language	Result	Execution time	Memory
288306		BeanZ	Dreaming (IOI13_dreaming)	C++14	100 / 100	131 ms	16544 KiB

dreaming

#include <bits/stdc++.h>
#include "dreaming.h"

using namespace std;

#define ll int
#define endl '\n'
const int N = 1e5 + 5;
ll dp[N], res, vis[N], lg, cur, d[N];
vector<pair<ll, ll>> node[N];
vector<ll> mem;
void FindFirstNode(ll u, ll p, ll dist){
        vis[u] = 1;
        mem.push_back(u);
        if (dist > lg){
                lg = dist;
                cur = u;
        }
        for (auto j : node[u]){
                if (j.first == p) continue;
                FindFirstNode(j.first, u, dist + j.second);
        }
}
void FindDia(ll u, ll p, ll dist){
        d[u] = dist;
        if (dist > lg){
                lg = dist;
                cur = u;
        }
        for (auto j : node[u]){
                if (j.first == p) continue;
                FindDia(j.first, u, dist + j.second);
        }
}
void DiaRev(ll u, ll p, ll dist){
        dp[u] = dist;
        for (auto j : node[u]){
                if (j.first == p) continue;
                DiaRev(j.first, u, dist + j.second);
        }
}
int travelTime(int N, int M, int L, int A[],int B[],int T[]){
        for (int i = 1; i <= M; i++){
                node[A[i - 1] + 1].push_back({B[i - 1] + 1, T[i - 1]});
                node[B[i - 1] + 1].push_back({A[i - 1] + 1, T[i - 1]});
        }
        vector<ll> pq;
        ll ans = 0;
        for (int i = 1; i <= N; i++){
                if (!vis[i]){
                        lg = -1;
                        mem.clear();
                        FindFirstNode(i, i, 0);
                        lg = -1;
                        FindDia(cur, cur, 0);
                        DiaRev(cur, cur, 0);
                        ll mn = 1e9;
                        for (auto j : mem){
                                mn = min(mn, max(d[j], dp[j]));
                        }
                        ans = max(ans, lg);
                        pq.push_back(mn);
                }
        }
        sort(pq.begin(), pq.end(), greater<ll>());
        if (pq.size() == 1) return ans;
        if (pq.size() == 2) return max(ans, pq[0] + pq[1] + L);
        return max(max(pq[1] + pq[2] + 2 * L, pq[0] + pq[1] + L), ans);
}
/*
int main(){
        ios_base::sync_with_stdio(false);
        cin.tie(0);
        if (fopen("VietCT.INP", "r")){
                freopen("VietCT.INP", "r", stdin);
                freopen("VietCT.OUT", "w", stdout);
        }
        int n, m, l;
        cin >> n >> m >> l;
        vector<int> a, b, t;
        for (int i = 1; i <= m; i++){
                int u, v, c;
                cin >> u >> v >> c;
                a.push_back(u);
                b.push_back(v);
                t.push_back(c);
        }
        cout << travelTime(n, m, l, a, b, t);
}
/*
12 8 2
0 8 4
8 2 2
2 7 4
5 11 3
5 1 7
1 3 1
1 9 5
10 6 3
*/

Compilation message (stderr)

dreaming.cpp:90:1: warning: "/*" within comment [-Wcomment]
   90 | /*
      |

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