Submission #1231398

#	Time	Username	Problem	Language	Result	Execution time	Memory
1231398		rhm_gan	Dreaming (IOI13_dreaming)	C++20	0 / 100	301 ms	68596 KiB

dreaming

#include <bits/stdc++.h>
#include "dreaming.h"
using namespace std;

const int N = 1e5;

struct Graph {
    int n;
    vector<vector<pair<int, int>>> g;
    vector<int> dp1, dp2, res;
    vector<array<int, 3>> edges;
    map<int, int> m, rev;
    int cnt;

    Graph() {
        cnt = 0;
    }

    void add(int a, int b, int w) {
        m[a] = m[b] = 1;
        edges.push_back({a, b, w});
        cnt++;
    }

    void compress() {
        int k = 0;
        for (auto [x, c] : m) {
            m[x] = k;
            rev[k] = x;
            k++;
        }
        n = k;
        g.resize(n);
        dp1.resize(n);
        dp2.resize(n);
        res.resize(n);
        for (auto [a, b, w] : edges) {
            a = m[a]; b = m[b];
            g[a].push_back({b, w});
            g[b].push_back({a, w});
        }
    }

    void dfs1(int u, int p) {
        for (auto [v, w] : g[u]) {
            if (v == p) continue;
            dfs1(v, u);
            if (dp1[v] + w >= dp1[u]) {
                dp2[u] = dp1[u];
                dp1[u] = dp1[v] + w;
            }
            else {
                dp2[u] = max(dp2[u], dp1[v] + w);
            }
        }
        res[u] = max(res[u], dp1[u]);
    }

    void dfs2(int u, int p, int d) {
        res[u] = max(res[u], d);
        for (auto [v, w] : g[u]) {
            if (v == p) continue;
            int k = 0;
            if (dp1[v] + w == dp1[u]) {
                k = dp2[u];
            }
            else {
                k = dp1[u];
            }
            dfs2(v, u, max(k, d) + w);
        }
    }

    int findmin() {
        compress();
        dfs1(0, -1);
        dfs2(0, -1, 0);
        int mn = 1e9;
        for (int i = 0; i < n; i++) {
            if (res[i] != 0) {
                mn = min(mn, res[i]);
            }
        }
        for (int i = 0; i < n; i++) {
            if (res[i] == mn) {
                return rev[i];
            }
        }
        return -1;
    }

    bool empty() {
        return cnt == 0;
    }

    void clear() {
        g.clear();
        dp1.clear();
        dp2.clear();
        res.clear();
        m.clear();
        rev.clear();
        cnt = n = 0;
    }
};

vector<pair<int, int>> adj[N];

Graph g[N];
bool vis[N];

void dfs(int u, int id) {
    vis[u] = 1;
    for (auto [v, w] : adj[u]) {
        if (!vis[v]) {
            g[id].add(u, v, w);
            dfs(v, id);
        }
    }
}

int travelTime(int n, int m, int l, int a[], int b[], int t[]) {
    Graph res;
    vector<bool> is(n);
    for (int i = 0; i < m; i++) {
        int u = a[i], v = b[i], w = t[i];
        is[u] = is[v] = 1;
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
        res.add(u, v, w);
    }

    int M = 0;
    for (int i = 0; i < n; i++) {
        if (!vis[i]) {
            dfs(i, M++);
        }
    }

    vector<int> v;
    for (int i = 0; i < n; i++) {
        if (!is[i]) {
            v.push_back(i);
        }
    }

    for (int i = 0; i < N; i++) {
        if (!g[i].empty()) {
            v.push_back(g[i].findmin());
        }
    }

    for (int i = 1; i < v.size(); i++) {
        res.add(v[i], v[i - 1], l);
    }

    int id = res.findmin();
    int ans = 0;
    for (int i = 0; i < N; i++) {
        ans = max(ans, res.res[i]);
    }

    return ans;
}

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