Submission #595041

#	Time	Username	Problem	Language	Result	Execution time	Memory
595041		pakhomovee	Dreaming (IOI13_dreaming)	C++17	100 / 100	313 ms	18424 KiB

dreaming

#include "dreaming.h"
#include <vector>
#include <unordered_map>
#include <deque>
#include <iostream>
#include <set>

using namespace std;

const int maxn = 1e5;
const int inf = 2e9;
bool used[maxn];
int cnt = 0;

unordered_map<int, int> dst(int v, vector<vector<pair<int, int>>> &g) {
    unordered_map<int, int> d;
    deque<int> q;
    q.push_back(v);
    d[v] = 0;
    while (!q.empty()) {
        int v = q.front();
        q.pop_front();
        for (auto [u, w] : g[v]) {
            if (!d.count(u)) {
                d[u] = d[v] + w;
                q.push_back(u);
            }
        }
    }
    return d;
}

pair<int, int> goFar(int v, vector<vector<pair<int, int>>> &g) {
    auto d1 = dst(v, g);
    int best = v;
    for (auto [u, x] : d1) {
        if (d1[best] < x) {
            best = u;
        }
        ++cnt;
        used[u] = true;
    }
    return { best, d1[best] };
}

pair<int, int> findDiam(int v, vector<vector<pair<int, int>>> &g) {
    int leafe = goFar(v, g).first;
    int best = goFar(leafe, g).first;
    int best1 = goFar(best, g).first;
    return { best, best1 };
}

int findDiamLen(int v, vector<vector<pair<int, int>>> &g) {
    int leafe = goFar(v, g).first;
    int best = goFar(leafe, g).first;
    return goFar(best, g).second;
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    vector<vector<pair<int, int>>> g(N);
    for (int i = 0; i < M; ++i) {
        int u = A[i], v = B[i];
        g[u].push_back({ v, T[i] });
        g[v].push_back({ u, T[i] });
    }
    vector<pair<int, int>> dims;
    multiset<pair<int, int>> s;
    for (int i = 0; i < N; ++i) {
        if (!used[i]) {
            cnt = 0;
            auto [u, v] = findDiam(i, g);
            auto d1 = dst(u, g);
            auto d2 = dst(v, g);
            int vs = -1;
            int b1 = inf;
            for (auto [u, l] : d1) {
                if (b1 > max(l, d2[u])) {
                    b1 = max(l, d2[u]);
                    vs = u;
                }
            }
            s.insert({ b1, vs });
        }
    }
    while (s.size() != 1) {
        auto [l1, u1] = *s.begin();
        s.erase(s.begin());
        auto [l2, u2] = *s.rbegin();
        auto pt = s.end();
        --pt;
        s.erase(pt);
        g[u1].push_back({ u2, L });
        g[u2].push_back({ u1, L });
        if (l1 > l2) {
            swap(l1, l2);
            swap(u1, u2);
        }
        s.insert({ max(l2, l1 + L), u2 });
    }
    return findDiamLen(0, g);
}

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