Submission #238569

#	Time	Username	Problem	Language	Result	Execution time	Memory
238569		arbor	Dreaming (IOI13_dreaming)	C++14	100 / 100	137 ms	17016 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
const int MN = 1e5 + 5;
vector<pii> g[MN];
int rt, D, R, dis[MN];
bool vis[MN];

void dfs(int u, int p, int d, bool qu) {
    vis[u] = true;
    if (d >= D) D = d, rt = u;
    if (qu) R = min(R, max(d, dis[u]));
    else dis[u] = d;
    for (pii e : g[u]) if (e.first != p) {
        dfs(e.first, u, d + e.second, qu);
    }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    for (int i = 0; i < M; i++) {
        int u = A[i], v = B[i], w = T[i];
        g[u].emplace_back(v, w);
        g[v].emplace_back(u, w);
    }
    vector<pii> lens;
    for (int i = 0; i < N; i++) {
        if (!vis[i]) {
            D = 0, R = INT_MAX;
            dfs(i, -1, 0, 0);
            dfs(rt, -1, 0, 0);
            dfs(rt, -1, 0, 1);
            lens.emplace_back(R, D);
        }
    }
    sort(lens.rbegin(), lens.rend());
    int mn = lens[0].second;
    if (lens.size() >= 2) mn = max(mn, lens[0].first + L + lens[1].first);
    if (lens.size() >= 3) mn = max(mn, lens[1].first + 2 * L + lens[2].first);
    return mn;
}

/* 
int main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    int a[] = {0,8,2,5,5,1,1,10};
    int b[] = {8,2,7,11,1,3,9,6};
    int c[] = {4,2,4,3,7,1,5,3};
    cout << travelTime(12,8,2,a,b,c) << '\n';
    return 0;
}   
*/

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