Submission #1114751

#	Time	Username	Problem	Language	Result	Execution time	Memory
1114751		asli_bg	Duathlon (APIO18_duathlon)	C++11	0 / 100	72 ms	44732 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;

#define int long long

#define fi first
#define se second
#define all(x) x.begin(),x.end()
#define sp <<' '<<
#define pb push_back

#define FOR(i,a) for(int i=0;i<(a);i++)
#define FORE(i,a,b) for(int i=(a);i<(b);i++)

#define cont(a) for(auto el:a) cout<<el<<' '; cout<<endl;
#define contp(a) for(auto el:a) cout<<el.fi<<'-'<<el.se<<' ';cout<<endl;

#define DEBUG(x) cout<<#x sp ":" sp x<<endl;

typedef vector<int> vi;
typedef pair<int,int> pii;
typedef vector<pii> vii;
typedef long long ll;

#define endl '\n'
#define mid (l+r)/2

const int MAXN=1e5+5;

int n,m;
vi adj[MAXN];
int ans;

/*----------BLOCK-CUT TREE----------- */

bool vis[MAXN], isarc[MAXN];
int dep[MAXN], low[MAXN];

vi st;

vi bcc[MAXN*2];

int cnt; //şuanki grafta kaç eleman var

int ind;

void dfs(int nd, int ata,int h){
    dep[nd]=h;
    low[nd]=h;

    int ch=0;
    st.pb(nd);

    cnt++;

    for(auto kom:adj[nd]){
        if(kom==ata) continue;
        if(vis[kom]){
            if(dep[kom]<dep[nd]) low[nd]=min(low[nd],dep[kom]);
            continue;
        }

        vis[kom]=true;
        dfs(kom,nd,h+1);
        
        ch++;

        if(low[kom]>=dep[nd]){ //we should create new block
            //komsuyu tüm graftan ayıran node == nd

            ind++;
            bcc[nd].pb(ind); //nodedan yeni bloğa

            int el;  
            do{
                el=st.back();
                st.pop_back();
                bcc[ind].pb(el);
            }while(el!=kom); //bloktan elemanlara edge çek

            if(ata!=-1) isarc[nd]=true;
        }

        low[nd]=min(low[nd],low[kom]);
    }

    if(ata==-1 and ch>1) isarc[nd]=true; 
}

/*----------DFS----------- */

int sub[MAXN];
bool vis2[MAXN];

void dfs2(int nd,int ata){

    sub[nd]=(nd<=n); //ben blok muyum yoksa node muyum

    for(auto kom:bcc[nd]){
        if(kom==ata) continue;
        if(vis2[kom]) continue;

        vis2[kom]=true;
        dfs2(kom,nd);
        sub[nd]+=sub[kom];

        if(nd>n){
            //ben bloksam
            //bcc[nd].size() --> bende kaç eleman var
            int bir=bcc[nd].size(); //bu bloktan 1 tane
            int iki=sub[kom]*(sub[kom]-1); //subtreemdeki nodelardan 2 tane seç

            ans-=max(0LL,bir*iki);
        }
    }

    //beni root kabul edip hesaplama yapıyorum
    //benim üstümde kalan subtreeyi hesaplamadık

    if(nd>n){
        int bir=bcc[nd].size();
        int iki=(cnt-sub[nd])*(cnt-sub[nd]-1);
        ans-=bir*iki;
    }
}

signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin>>n>>m;
    FOR(i,m){
        int a,b;
        cin>>a>>b;
        adj[a].pb(b);
        adj[b].pb(a);
    }

    ans=n*(n-1)*(n-2);

    ind=n;
    FORE(j,1,n+1){
        if(!vis[j]){
            vis[j]=true;

            dfs(j,-1,0);

            dfs2(j,-1);
        }
    }

    cout<<ans<<endl;
}

• 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