Submission #575138

#	Time	Username	Problem	Language	Result	Execution time	Memory
575138		d4xn	Dreaming (IOI13_dreaming)	C++17	100 / 100	95 ms	15180 KiB

dreaming

#pragma GCC optimize ("Ofast")
#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;

const int N = 1e5+5, inf = INT_MAX;

int n, mxDis, furthest, mn, ans;
vector<int> dp, distances;
vector<pair<int, int>> adj[N];
bitset<N> vis;

void getFurthest(int u, int par, int d) {
    vis[u] = 1;
    if (d > mxDis) {
        mxDis = d;
        furthest = u;
        ans = max(ans, d);
    }
    for (auto &[v, w] : adj[u]) {
        if (v == par) continue;
        getFurthest(v, u, d+w);
    }
}

void dfs(int u, int par, int d, bool b) {
    vis[u] = 1;
    dp[u] = max(dp[u], d);

    if (b && dp[u] < mn) mn = dp[u];

    for (auto &[v, w] : adj[u]) {
        if (v == par) continue;
        dfs(v, u, d+w, b);
    }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    n = N;
    ans = 0;
    dp.resize(n, 0);
    for (int i = 0; i < M; i++) {
        adj[A[i]].push_back(make_pair(B[i], T[i]));
        adj[B[i]].push_back(make_pair(A[i], T[i]));
    }

    for (int i = 0; i < n; i++) {
        if (vis[i]) continue;
        mxDis = -1;
        getFurthest(i, -1, 0);
        int a = furthest;

        mxDis = -1;
        getFurthest(a, -1, 0);
        int b = furthest;

        mn = inf;
        dfs(a, -1, 0, 0);
        dfs(b, -1, 0, 1);
        distances.push_back(mn);
    }
    sort(distances.rbegin(), distances.rend());

    if (distances.size() >= 3) {
        return max({ans, 2*L + distances[1] + distances[2], L + distances[0] + distances[1]});
    }
    else if (distances.size() == 2) {
        return max(ans, L + distances[0] + distances[1]);
    }
    else {
        return max(ans, distances[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