Submission #112095

#	Time	Username	Problem	Language	Result	Execution time	Memory
112095		Sa1loum	Duathlon (APIO18_duathlon)	C++14	0 / 100	131 ms	11252 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;
#define IO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define mem(a,b) memset(a, b, sizeof(a))
#define F first
#define S second
#define Si size
#define pb(x) push_back(x)
typedef double D;
typedef long long ll;
typedef long double ld;
const int MOD=(int)1e9+7,MAX=(int)1e5+10;
int n,m,vis[MAX],dp[MAX];
vector <int> v[MAX];
bool cyc=0;
int dfs(int i,int com) {
    if (vis[i]) {cyc=1; return 0;}
    vis[i]=1;
    int ret=1;
    for (auto it:v[i]) {
        if (it==com) continue;
        ret+=dfs(it,i);
    }
    return ret;
}
int fac(int n) {
    if (dp[n]!=-1) return dp[n];
    if (n<=2) return dp[n]=2;
    return dp[n]=fac(n-1)*n;
}
int main()
{
    mem(dp,-1);
    cin>>n>>m;
    for (int i=0;i<m;i++) {
        int u,x;
        cin>>u>>x;
        v[u].push_back(x);
        v[x].push_back(u);
    }
    ll ans=0;
    for (int i=1;i<=n;i++) {
        if (vis[i]) continue;
        cyc=0;
        int l=dfs(i,-1);
        if (l<3) ;
        else if (cyc) {
            ans+=fac(l);
        }
        else {
            ans+=((l*(l-1)*(l-2))/fac(3))*2;
        }
    }
    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