제출 #924345

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
924345		codefox	철인 이종 경기 (APIO18_duathlon)	C++14	0 / 100	123 ms	41356 KiB

count_triplets

#include<bits/stdc++.h>
    
using namespace std;
    
#define int ll    
#define ll long long
    
vector<vector<int>> graph;
vector<vector<int>> cgraph;
vector<int> comp;
vector<int> art;
vector<int> low;
vector<int> num;
vector<int> vis;
stack<int> s;
int c = 0;
int d = 0;
int root = 0;
int sub = 0;
vector<int> subtree;
vector<ll> compsize;
ll sol = 0;
ll n, m;
    
void dfs(int i, int p)
{
    num[i] = low[i] = ++c;
    s.push(i);
    for (int ele:graph[i])
    {
        if (i==root) sub++;
        if (ele == p) continue;
        if (!num[ele]) 
        {
            dfs(ele, i);
            if (low[ele]>=num[i]) art[i] = 1;
            if (low[ele]==num[i])
            {
                while(s.top() != i)
                {
                    comp[s.top()] = d;
                    compsize[d]++;
                    s.pop();
                }
                comp[i] = d;
                compsize[d]++;
                s.pop();
                d++;
            }
        }
        low[i] = min(low[i], low[ele]);
    }
    if (num[i]==low[i] && comp[i]==-1)
    {
        art[i] = 1;
        while (s.top() != i)
        {
            comp[s.top()] = d;
            compsize[d]++;
            s.pop();
        }
        comp[i] = d;
        compsize[d]++;
        s.pop();
        d++;
    }
}
    
int dfs2(int i)
{
    vis[i] = 1;
    ll ss = 0;
    vector<int> cs;
    for (int ele:cgraph[i])
    {
        if (!vis[ele]) 
        {
            int h = dfs2(ele);
            sol -= compsize[i]*(h-compsize[ele])*(h-compsize[ele]-1);
            sol -= compsize[i]*compsize[ele]*(h-compsize[ele])*2;
            cs.push_back(ele);
            ss+=h;
        }
    }
    for (int ele:cs)
    {
        sol -= compsize[ele]*(sub-ss-compsize[i])*(sub-ss-compsize[i]-1);
        sol -= compsize[ele]*compsize[i]*(sub-ss-compsize[i])*2;
    }
    return ss+compsize[i];
}
    
int32_t main()
{
    //freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);
    
    cin >> n >> m;
    graph.assign(n, vector<int>());
    cgraph.assign(5*n, vector<int>());
    compsize.assign(5*n, 0);
    low.assign(n, 0);
    num.assign(n, 0);
    comp.assign(n, -1);
    art.assign(n, 0);
    vis.assign(5*n, 0);
    subtree.assign(5*n, 0);
    
    for (int i =0; i < m; i++)
    {
        int a, b;
        cin >> a >> b;
        a--; b--;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    
    for (int i = 0; i < n; i++)
    {
        if (!num[i]) 
        {
            sub = 0;
            root = i;
            c = 0;
            dfs(i, -1);
            subtree[comp[i]] = c;
            sol += max((ll)0, c*(c-1)*(c-2));
            if (sub==1) art[i] = 0;
        }
    }
    
    for (int i = 0; i <n; i++)
    {
        if (art[i])
        {
            compsize[comp[i]]--;
            comp[i] = d;
            subtree[d] = subtree[comp[i]];
            subtree[comp[i]]=0;
            compsize[d] = 1;
            d++;
        }
    }
    for (int i = 0; i <n; i++)
    {
        if (art[i])
        {
            for (int ele:graph[i])
            {
                if (art[ele] && ele > i) 
                {
                    cgraph[comp[i]].push_back(d);
                    cgraph[d].push_back(comp[i]);
                    cgraph[d].push_back(comp[ele]);
                    cgraph[comp[ele]].push_back(d);
                    d++;
                    continue;
                }
                cgraph[comp[i]].push_back(comp[ele]);
                cgraph[comp[ele]].push_back(comp[i]);
            }
        }
    }
    
    for (int i = 0; i < n; i++)
    {
        if (!vis[comp[i]])
        {
            sub = subtree[comp[i]];
            dfs2(comp[i]);
        }
    }
    cout << sol << "\n";
    
    return 0;
}

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