Submission #829646

#	Time	Username	Problem	Language	Result	Execution time	Memory
829646		FatihSolak	Duathlon (APIO18_duathlon)	C++17	31 / 100	77 ms	27376 KiB

count_triplets

#include <bits/stdc++.h>
#define N 100005
using namespace std;
vector<int> adj[N];
vector<int> adj2[N];
vector<int> adj3[N];
int d[N];
int low[N];
vector<pair<int,int>> edges;
int totsize[N];
int val = 0;
void dfs(int v,int par){
    d[v] = d[par] + 1;
    low[v] = d[v];
    totsize[v] = 1;
    for(auto u:adj[v]){
        if(u == par)
            continue;
        if(d[u] != 0){
            low[v] = min(d[u],low[v]);
            if(d[v] < d[u]){
                adj2[v].push_back(u);
                adj2[u].push_back(v);
            }
        }
        else{
            dfs(u,v);
            totsize[v] += totsize[u];
            low[v] = min(low[v],low[u]);
            if(low[u] <= d[v]){
                adj2[v].push_back(u);
                adj2[u].push_back(v);
            }
            else{
                edges.push_back({u,v});
            }
        }
    }
}
int cnt[N];
int group[N];
int sub[N];
int n;
long long ans = 0;
void dfs2(int v){
    cnt[group[v]]++;
    for(auto u:adj2[v]){
        if(group[u])continue;
        group[u] = group[v];
        dfs2(u);
    }
}
void dfs3(int v,int par){
    sub[v] = cnt[v];
    for(auto u:adj3[v]){
        if(u == par)
            continue;
        dfs3(u,v);
        sub[v] += sub[u];
    }
    ans += 2 * (long long)cnt[v] * (cnt[v] - 1) * (val - cnt[v]);
    ans -= 2 * (long long)(cnt[v] - 1) * (val - cnt[v]);
    for(auto u:adj3[v]){
        if(u == par){
            ans += (long long)cnt[v] * (val - sub[v]) * (sub[v] - cnt[v]);
        }
        else{
            ans += (long long)cnt[v] * (val - sub[u] - cnt[v]) * (sub[u]);
        }
    }
}
void solve(){
    int m;
    cin >> n >> m;
    for(int i = 1;i<=m;i++){
        int u,v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    for(int i = 1;i<=n;i++){
        if(d[i] == 0)
            dfs(i,0);
    }
    for(int i = 1;i<=n;i++){
        if(group[i] == 0){
            group[i] = i;
            dfs2(i);
            ans += (long long)cnt[i] * (cnt[i]-1) * (cnt[i]-2);
        }
    }
    for(auto u:edges){
        adj3[group[u.first]].push_back(group[u.second]);
        adj3[group[u.second]].push_back(group[u.first]);
    }
    for(int i = 1;i<=n;i++){
        if(sub[i] == 0 && group[i] == i){
            val = totsize[i];
            dfs3(i,0);
        }
    }
    cout << ans;
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    #ifdef Local    
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    #endif
    int t = 1;
    //cin >> t;
    while(t--){
        solve();
    }
}

• 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