Submission #945509

#	Time	Username	Problem	Language	Result	Execution time	Memory
945509		GrandTiger1729	Hard route (IZhO17_road)	C++17	52 / 100	728 ms	262144 KiB

road

#include <bits/stdc++.h>
using namespace std;
 
int main()
{
    cin.tie(0)->sync_with_stdio(0);
    int n;
    cin >> n;
    vector<vector<int>> g(n);
    for (int i = 0; i < n - 1; i++)
    {
        int u, v;
        cin >> u >> v;
        u--, v--;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    vector<vector<pair<int, int>>> res(n);
    {
        vector<bool> vis(n);
        function<pair<int, int>(int)> dfs = [&](int u) -> pair<int, int>
        {
            res[u].resize(g[u].size());
            vis[u] = 1;
            pair<int, int> ret(0, 1);
            for (int i = 0; i < g[u].size(); i++)
            {
                int v = g[u][i];
                if (vis[v])
                {
                    continue;
                }
                res[u][i] = dfs(v);
                if (res[u][i].first > ret.first)
                {
                    ret = res[u][i];
                }
                else if (res[u][i].first == ret.first)
                {
                    ret.second += res[u][i].second;
                }
            }
            ret.first++;
            return ret;
        };
        dfs(0);
    }
    long long ans = 0, cnt = 1;
    auto update = [&](long long x, long long y)
    {
        if (y == 0)
        {
            return;
        }
        if (ans < x)
        {
            ans = x;
            cnt = y;
        }
        else if (ans == x)
        {
            cnt += y;
        }
    };
    {
        vector<bool> vis(n);
        function<void(int, pair<int, int>)> dfs = [&](int u, pair<int, int> cur)
        {
            vis[u] = 1;
            multiset<pair<int, int>> st;
            for (int i = 0; i < g[u].size(); i++)
            {
                int v = g[u][i];
                if (vis[v])
                {
                    continue;
                }
                st.insert(res[u][i]);
            }
            if (u != 0)
            {
                st.insert(cur);
            }
            if (st.size() >= 3)
            {
                auto it = --st.end();
                auto it3 = it--;
                auto it2 = it--;
                if (it->first == it3->first)
                {
                    int tot = it2->second + it3->second;
                    long long tot2 = 1ll * it2->second * it2->second + 1ll * it3->second * it3->second;
                    auto it4 = it;
                    while (it4->first == it->first)
                    {
                        tot += it4->second;
                        tot2 += 1ll * it4->second * it4->second;
                      	if (it4 == st.begin())
                        {
                            break;
                        }
                      	it4--;
                    }
                    update(1ll * (it->first + it2->first) * it3->first, (1ll * tot * tot - tot2) / 2);
                }
                else if (it2->first == it3->first)
                {
                    int tot = 0;
                    auto it4 = it;
                    while (it4->first == it->first)
                    {
                        tot += it4->second;
                      	if (it4 == st.begin())
                        {
                            break;
                        }
                      	it4--;
                    }
                    update(1ll * (it->first + it2->first) * it3->first, 1ll * tot * (it2->second + it3->second));
                }
                else if (it->first == it2->first)
                {
                    int tot = it2->second;
                    long long tot2 = 1ll * it2->second * it2->second;
                    auto it4 = it;
                    while (it4->first == it->first)
                    {
                        tot += it4->second;
                        tot2 += 1ll * it4->second * it4->second;
                      	if (it4 == st.begin())
                        {
                            break;
                        }
                      	it4--;
                    }
                    update(1ll * (it->first + it2->first) * it3->first, (1ll * tot * tot - tot2) / 2);
                }
                else
                {
                    int tot = 0;
                    auto it4 = it;
                    while (it4->first == it->first)
                    {
                        tot += it4->second;
                      	if (it4 == st.begin())
                        {
                          	break;
                        }
                      	it4--;
                    }
                    update(1ll * (it->first + it2->first) * it3->first, 1ll * tot * it2->second);
                }
            }
            map<int, int> mp;
            for (int i = 0; i < g[u].size(); i++)
            {
                int v = g[u][i];
                if (vis[v])
                {
                    continue;
                }
                mp[res[u][i].first] += res[u][i].second;
            }
            mp[cur.first] += cur.second;
            for (int i = 0; i < g[u].size(); i++)
            {
                int v = g[u][i];
                if (vis[v])
                {
                    continue;
                }
                mp[res[u][i].first] -= res[u][i].second;
                if ((--mp.end())->second == 0)
                {
                    mp.erase(--mp.end());
                }
                pair<int, int> x = *(--mp.end());
                x.first++;
                dfs(v, x);
                mp[res[u][i].first] += res[u][i].second;
            }
        };
        dfs(0, make_pair(0, 1));
    }
    cout << ans << ' ' << cnt << '\n';
    return 0;
}

Compilation message (stderr)

road.cpp: In lambda function:
road.cpp:26:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   26 |             for (int i = 0; i < g[u].size(); i++)
      |                             ~~^~~~~~~~~~~~~
road.cpp: In lambda function:
road.cpp:71:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |             for (int i = 0; i < g[u].size(); i++)
      |                             ~~^~~~~~~~~~~~~
road.cpp:155:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  155 |             for (int i = 0; i < g[u].size(); i++)
      |                             ~~^~~~~~~~~~~~~
road.cpp:165:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  165 |             for (int i = 0; i < g[u].size(); i++)
      |                             ~~^~~~~~~~~~~~~

• Subtask 1: 19 / 19
• Subtask 2: 33 / 33
• Subtask 3: 0 / 48