Submission #864592

#	Time	Username	Problem	Language	Result	Execution time	Memory
864592		vnm06	Duathlon (APIO18_duathlon)	C++14	23 / 100	40 ms	19788 KiB

count_triplets

#include<bits/stdc++.h>
#define endl '\n'

using namespace std;

long long n, m;
vector<int> gr[300005];

long long ans=0, br=0;
bool used[300005], used_br[300005];
long long dp_v[300005];

void find_br(int v)
{
    used_br[v]=1;
    br++;
    int brs=gr[v].size();
    for(int i=0; i<brs; i++)
    {
        if(used_br[gr[v][i]]) continue;
        find_br(gr[v][i]);
    }
}

void dfs(int v)
{
    used[v]=1;
    dp_v[v]=1;
    int brs=gr[v].size();
    long long sumv=0;
    for(int i=0; i<brs; i++)
    {
        if(used[gr[v][i]]) continue;
        dfs(gr[v][i]);
        ans+=dp_v[gr[v][i]]*sumv;
        sumv+=dp_v[gr[v][i]];
        dp_v[v]+=dp_v[gr[v][i]];
    }
    ans+=sumv*(br-sumv-1);
}

void solve_component(int v)
{
    br=0;
    find_br(v);
    dfs(v);
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin>>n>>m;
    for(int i=0; i<m; i++)
    {
        int v, u;
        cin>>v>>u;
        gr[v].push_back(u);
        gr[u].push_back(v);
    }
    for(int i=1; i<=n; i++)
    {
        if(used[i]) continue;
        solve_component(i);
    }
    cout<<2*ans<<endl;
    return 0;
}
/**
8 7
1 2
2 3
2 4
3 5
5 6
6 7
6 8
*/

• 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