Submission #1094598

#	Time	Username	Problem	Language	Result	Execution time	Memory
1094598		vjudge1	Duathlon (APIO18_duathlon)	C++17	0 / 100	62 ms	37068 KiB

count_triplets

#include <bits/stdc++.h>

using namespace std;

typedef pair<long long,long long> PLL;
typedef long long LL;

#define int long long
#define ln '\n'
#define faster {ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);}

#define all(v) v.begin(),v.end()

int mod = 998244353;
const int N = 4e5 + 10;
const int inf = 1e9;


vector<PLL> g[N];
vector<int> comp[N];
int disc[N], low[N], mark[N], vis[N], timer = 1, cur = 1;
vector<int> currcomp;

void dfs(int u, int p){
    disc[u] = low[u] = timer++; currcomp.push_back(u);
    bool fl = 1;
    for(auto [v, id]: g[u]){
        if(v == p && fl) {fl = 0; continue;}
        if(disc[v]){
            low[u] = min(low[u], disc[v]);
        }else{
            dfs(v, u);
            low[u] = min(low[u], low[v]);
            if(disc[u] < low[v]){
                mark[id] = 1;
            }
        }
    }
}

void colorComponents(int u, int color){
    if(vis[u]) return;
    comp[color].push_back(u);
    vis[u] = color;
    for(auto [v, id]: g[u]){
        if(mark[id]) continue;
        colorComponents(v, color);
    }
}

void solve(int test){
    int n, m, q; cin>>n>>m;
    for(int i = 0, u, v; i < m; i++){
        cin>>u>>v;
        g[u].push_back({v, i}); g[v].push_back({u, i});
    }

    auto nC2 = [&](LL n){
        return n * (n - 1) / 2;
    };
    auto nC3 = [&](LL n){
        return n * (n - 1) * (n - 2) / 6;
    };
    LL ans = 0;
    for(int i = 1; i <= n; i++){
        if(!disc[i]){
            dfs(i, -1);
            int SZ = currcomp.size(), last = cur;
            ans += nC3(SZ);
            for(auto u: currcomp){
                if(!vis[u]){
                    colorComponents(u, cur++);
                }
            }
            for(int j = last; j < cur; j++){
                int sz = comp[j].size(); //cout<<sz<<'\n';
                LL tmp = nC3(sz) * 2 + nC2(sz - 1) * (SZ - sz);
                ans += tmp;
            }
        }
    }
    
    cout<<ans * 2<<'\n';
}

signed main(){
    faster
    int t = 1; 
    // cin>>t;
    for(int i = 1; i <= t; i++){
        solve(i);
    }
    return 0;
}

Compilation message (stderr)

count_triplets.cpp: In function 'void solve(long long int)':
count_triplets.cpp:52:15: warning: unused variable 'q' [-Wunused-variable]
   52 |     int n, m, q; cin>>n>>m;
      |               ^

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