Submission #552497

#	Time	Username	Problem	Language	Result	Execution time	Memory
552497		zaneyu	Duathlon (APIO18_duathlon)	C++14	8 / 100	57 ms	11084 KiB

count_triplets

/*input
4 4
1 2
2 3
3 4
4 1
*/
#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 lowb(x) x&(-x)
#define ll long long
#define MNTO(x,y) x=min(x,y)
#define REP1(i,n) for(int i=1;i<=n;i++)
int d;
vector<int> v[maxn];
bool ok[maxn];
int vis[maxn];
bool cyc=0;
ll sz=0;
void dfs(int u,int p){
    vis[u]=1;
    ++sz;
    for(int x:v[u]){
        if(x==p) continue;
        if(!vis[x]){
            dfs(x,u);
        }
        else{
            cyc=1;
        }
    }
}
ll ans=0;
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]){
            sz=0;
            cyc=0;
            dfs(i,-1);
            if(cyc) ans+=sz*(sz-1)*(sz-2);
            else ans+=sz*(sz-1)*(sz-2)/3;
        }
    }
    cout<<ans;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 8 / 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