Submission #288292

#	Time	Username	Problem	Language	Result	Execution time	Memory
288292		BeanZ	Dreaming (IOI13_dreaming)	C++14	77 / 100	1085 ms	15224 KiB

dreaming

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

using namespace std;

#define ll long long
#define endl '\n'
const int N = 1e5 + 5;
ll dp[N], res, vis[N], vis2[N], diameter;
vector<pair<ll, ll>> node[N];
void dfsFirst(ll u){
        vis[u] = 1;
        for (auto j : node[u]){
                if (vis[j.first]) continue;
                dfsFirst(j.first);
                dp[u] = max(dp[u], dp[j.first] + j.second);
        }
}
void reroot(ll u, ll v){
        dp[u] = 0;
        for (auto j : node[u]){
                if (j.first == v) continue;
                dp[u] = max(dp[u], dp[j.first] + j.second);
        }
        dp[v] = 0;
        for (auto j : node[v]){
                dp[v] = max(dp[v], dp[j.first] + j.second);
        }
        if (res >= dp[v]){
                res = min(res, dp[v]);
                vector<ll> mem;
                for (auto j : node[v]){
                        mem.push_back(dp[j.first] + j.second);
                }
                diameter = 0;
                if (mem.size()){
                        sort(mem.begin(), mem.end());
                        for (int i = mem.size() - 1; i >= max((ll)mem.size() - 2, 0ll); i--){
                                diameter += mem[i];
                        }
                }
        }
}
void dfs(ll u, ll p){
        for (auto j : node[u]){
                if (j.first == p) continue;
                reroot(u, j.first);
                dfs(j.first, u);
                reroot(j.first, u);
        }
}
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]});
        }
        priority_queue<ll> pq;
        ll ans = 0;
        for (int i = 1; i <= N; i++){
                if (!vis[i]){
                        diameter = 0;
                        dfsFirst(i);
                        res = dp[i];
                        dfs(i, i);
                        ans = max(ans, diameter);
                        pq.push(res);
                }
        }
        ll root = pq.top();
        pq.pop();
        ll mx = -1e18;
        ll res = root;
        while (pq.size()){
                ans = max(ans, pq.top() + 2 * L + mx);
                ans = max(ans, pq.top() + L + root);
                mx = max(mx, pq.top());
                pq.pop();
        }
        return 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 + 1);
                b.push_back(v + 1);
                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: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:72:12: warning: unused variable 'res' [-Wunused-variable]
   72 |         ll res = root;
      |            ^~~

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 18 / 18
• Subtask 5: 12 / 12
• Subtask 6: 0 / 23