Submission #552393

#	Time	Username	Problem	Language	Result	Execution time	Memory
552393		zaneyu	Duathlon (APIO18_duathlon)	C++14	23 / 100	71 ms	10752 KiB

count_triplets

/*input
4 3
1 2
2 3
3 4
*/
#include<bits/stdc++.h>
using namespace std;
#define REP(i,n) for(int i=0;i<n;i++)
const int maxn=1e5+5;
#define pb push_back
#define ll long long
int dep[maxn];
int vis[maxn];
vector<int> v[maxn];
ll ans=0;
int c;
int dfs(int u){
    vis[u]=1;
    int sz=1;
    for(int x:v[u]){
        if(!vis[x]){
            sz+=dfs(x);
        }
    }
    return sz;
}
int dfs2(int u){
    vis[u]=2;
    int sz=1;
    for(int x:v[u]){
        if(vis[x]==1){
            int tmp=dfs2(x);
            ans+=1LL*tmp*(c-tmp);
            sz+=tmp;
        }
    }
    return sz;
}
int main(){
    ios::sync_with_stdio(false),cin.tie(0);
    int n,m;
    cin>>n>>m;
    REP(i,m){
        int a,b;
        cin>>a>>b;
        --a,--b;
        v[a].pb(b),v[b].pb(a);
    }
    REP(i,n){
        if(!vis[i]){
            c=dfs(i);
            ans-=1LL*c*(c-1)/2;
            dfs2(i);
        }
    }
    cout<<ans*2<<'\n';
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 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