Submission #860035

#	Time	Username	Problem	Language	Result	Execution time	Memory
860035		victor_gao	Duathlon (APIO18_duathlon)	C++17	100 / 100	95 ms	42180 KiB

count_triplets

//#pragma GCC optimize("Ofast,unroll-loops,O3")
//#pragma GCC optimize("avx,avx2,sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,fma,tune=native")
#include<bits/stdc++.h>
//#include<bits/extc++.h>
//#pragma pack(1)
#define fast ios::sync_with_stdio(0); cin.tie(0);
#define int long long
#define pii pair<int,int>
#define x first
#define y second
#define N 200015
using namespace std;
//using namespace __gnu_pbds;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//typedef tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update> order_multiset;
//typedef tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> order_set;
int n,m,dfn[N],low[N],sz[N],have[N],nbcc=0,t=0,ans=0;
bool vis[N];
stack<int>st;
vector<int>g[N],bcc[N];
vector<int>G[N];
void tarjan(int p,int lp){
    dfn[p]=low[p]=++t;
    st.push(p);
    for (auto i:g[p]){
        if (!dfn[i]){
            tarjan(i,p);
            low[p]=min(low[p],low[i]);
            if (dfn[p]<=low[i]){
                nbcc++;
                for (int x=0;x!=i;st.pop()){
                    x=st.top();
                    bcc[nbcc].push_back(x);
                }
                bcc[nbcc].push_back(p);
            }
        }
        else low[p]=min(low[p],dfn[i]);
    }
}
void build(){
    for (int i=1;i<=nbcc;i++){
        for (auto j:bcc[i]){
            G[i+n].push_back(j);
            G[j].push_back(i+n);
        }
    }
}
int get_size(int p,int lp){
    int tans=(p<=n);
    for (auto i:G[p]){
        if (i!=lp)
            tans+=get_size(i,p);
    }
    return tans;
}
void dfs(int p,int lp,int now){
    vis[p]=1; sz[p]+=(p<=n);
    for (auto i:G[p]){
        if (i!=lp){
            dfs(i,p,now);
            ans=(ans+have[p]*sz[i]*(sz[p]));
            sz[p]+=sz[i];
        }
    }
    ans=(ans+have[p]*(now-sz[p])*sz[p]);
}
signed main(){
    fast
    cin>>n>>m;
    for (int i=1;i<=m;i++){
        int a,b; cin>>a>>b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    for (int i=1;i<=n;i++){
        have[i]=-1;
        if (!dfn[i]){
            while (!st.empty()) st.pop();
            tarjan(i,0);
        }
    }
    build();
    for (int i=1;i<=nbcc;i++)
        have[i+n]=bcc[i].size();
    for (int i=1;i<=n+nbcc;i++){
        if (!vis[i]){
            int s=get_size(i,0);
            dfs(i,0,s);
        }
    }
    cout<<ans*2<<'\n';
}

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