Submission #107378

#	Time	Username	Problem	Language	Result	Execution time	Memory
107378		kuroni	Duathlon (APIO18_duathlon)	C++14	31 / 100	437 ms	37364 KiB

count_triplets

#include <iostream>
#include <cstdio>
#include <vector>
#include <cassert>
#include <algorithm>
using namespace std;
    
const int N = 100005;
    
int n, m, u, v, nod, cnt = 0, sz[2 * N], sub[2 * N], num[N], low[N];
long long ans = 0;
bool vis[2 * N];
vector<int> st, com[N], adj[N], cut[2 * N];
vector<vector<int>> bi;
    
void process(vector<int> &ve)
{
    sort(ve.begin(), ve.end());
    for (int i = 0; i < ve.size() - 1; i++)
        assert(ve[i] < ve[i + 1]);
    ve.erase(unique(ve.begin(), ve.end()), ve.end());
    ++nod;
    for (int &v : ve)
    {
        sz[nod]++;
        com[v].push_back(nod);
    }
}
    
void DFS(int u, int p = 0)
{
    low[u] = num[u] = ++cnt;
    st.push_back(u);
    for (int &v : adj[u])
        if (v != p)
        {
            if (num[v] > 0)
                low[u] = min(low[u], num[v]);
            else
            {
                DFS(v, u);
                low[u] = min(low[u], low[v]);
                if (low[v] >= num[u])
                {
                    int v; bi.push_back({});
                    do
                    {
                        v = st.back(); st.pop_back();
                        bi.back().push_back(v);
                    } while (u != v);
                    process(bi.back());
                    st.push_back(u);
                }
            }
        }
}
    
int get_subtree(int u, int p = 0)
{
    sub[u] = sz[u];
    for (int &v : cut[u])
        if (v != p)
            sub[u] += get_subtree(v, u);
    return sub[u];
}
    
void find_ans(int u, int tot)
{
    vis[u] = true;
    int ver = cut[u].size(), big = u > n;
    ans += 1LL * sz[u] * (sz[u] - 1) * (ver * big + sz[u] - 2);
    ans += 2LL * sz[u] * ((ver - 1) * big + sz[u] - 1) * (tot - sz[u]);
    int cur = tot - sub[u];
    for (int &v : cut[u])
        if (!vis[v])
        {
            find_ans(v, tot);
            ans += 2LL * cur * ((ver - 2) * big + sz[u]) * sub[v];
            cur += sub[v];
        }
}
    
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> n >> m;
    nod = n;
    while (m--)
    {
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for (int i = 1; i <= n; i++)
        if (num[i] == 0)
            DFS(i);
    for (int i = 1; i <= n; i++)
        if (com[i].size() > 1)
        {
            sz[i] = 1;
            for (int &v : com[i])
            {
                sz[v]--;
                cut[i].push_back(v);
                cut[v].push_back(i);
            }
        }
    for (int i = 1; i <= nod; i++)
        if (!vis[i])
            find_ans(i, get_subtree(i));
    cout << ans;
}

Compilation message (stderr)

count_triplets.cpp: In function 'void process(std::vector<int>&)':
count_triplets.cpp:19:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < ve.size() - 1; i++)
                     ~~^~~~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 8 / 8
• Subtask 4: 10 / 10
• Subtask 5: 13 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10