Submission #990819

#	Time	Username	Problem	Language	Result	Execution time	Memory
990819		stdfloat	Dreaming (IOI13_dreaming)	C++17	14 / 100	32 ms	18524 KiB

dreaming

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

#define ff  first
#define ss  second
#define pii pair<int, int>

int cnt;

vector<int> v, u, vis;

vector<pii> a;

vector<vector<pii>> E;

int dfsv(int x, int p = -1) {
    for (auto [i, w] : E[x])
        if (i != p) v[x] = max(v[x], w + dfsv(i, x));

    return v[x];
}

void dfsu(int x) {
    vis[x] = cnt;

    for (auto [i, w] : E[x])
        if (!vis[i]) a.push_back({w + v[i], i});

    sort(a.rbegin(), a.rend());

    for (auto [i, w] : E[x])
        if (!vis[i]) u[i] = w + max(u[x], (a[0].ss != i ? a[0].ff : (1 < (int)a.size() ? a[1].ff : 0)));

    a.clear();
    for (auto [i, w] : E[x])
        if (!vis[i]) dfsu(i);
}

int travelTime(int n, int m, int L, int A[], int B[], int T[]) {
    E.assign(n, {});
    for (int i = 0; i < m; i++) {
        E[A[i]].push_back({B[i], T[i]});
        E[B[i]].push_back({A[i], T[i]});
    }

    vis.assign(n, 0);
    v.assign(n, 0); u.assign(n, 0);
    for (int i = 0; i < n; i++) {
        if (!vis[i]) {
            cnt++;
            dfsv(i); dfsu(i);
        }
    }

    int mx = 0;
    vector<int> mn(n, INT_MAX);
    for (int i = 0; i < n; i++) {
        mx = max({mx, v[i], u[i]});
        mn[vis[i]] = min(mn[vis[i]], max(v[i], u[i]));
    }

    sort(mn.begin(), mn.end());
    while (mn.back() == INT_MAX) mn.pop_back();
    reverse(mn.begin(), mn.end());

    set<int> s(vis.begin(), vis.end());
    assert((int)s.size() == 2);

    if (1 < (int)mn.size()) mx = max(mx, mn[0] + L + mn[1]);
    if (2 < (int)mn.size()) mx = max(mx, mn[1] + (L << 1) + mn[2]);

    return mx;
}

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