Submission #1138871

#	Time	Username	Problem	Language	Result	Execution time	Memory
1138871		Zbyszek99	Duathlon (APIO18_duathlon)	C++20	100 / 100	128 ms	50776 KiB

count_triplets

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;

vi graph_tree[200005];
vi graph[1000015];

int pre[100005];
int low[100005];
int cur_pre = 0;
ll subtree[200005];

bool odw[200005];
int cur_comp = 1;
ll ans = 0;
int n,m;
ll tree_siz = 0;

stack<int> st;

void calc_pre(int v, int pop)
{
    tree_siz++;
    odw[v] = 1;
    pre[v] = cur_pre++;
    low[v] = pre[v];
    forall(it,graph[v])
    {
        if(odw[it] == 1)
        {
            if(it != pop)
            {
         //       cout << v << " " << it << " " << pop << " low\n";
                low[v] = min(low[v],pre[it]);
            }
        }
        else
        {
            calc_pre(it,v);
            low[v] = min(low[v],low[it]);
        }
    }
}

void calc_comps(int v, int pop)
{
    st.push(v);
    odw[v] = 0;
    forall(it,graph[v])
    {
        if(odw[it] == 0) continue;
        calc_comps(it,v);
        if(low[it] >= pre[v])
        {
            graph_tree[v].pb(cur_comp+n);
            while(siz(graph_tree[cur_comp+n]) == 0 || graph_tree[cur_comp+n][siz(graph_tree[cur_comp+n])-1] != it)
            {
                graph_tree[cur_comp+n].pb(st.top());
                st.pop();
            }
            cur_comp++;
        }
    }
}

int dfs_ans(int v, int pop)
{
    if(v <= n) subtree[v] = 1;
    odw[v] = 1;
  //  cout << v << " v\n";
    forall(it,graph_tree[v])
    {
        if(it != pop)
        {
            subtree[v] += dfs_ans(it,v);
            if(v > n)
            {
                ans -= siz(graph_tree[v]) * subtree[it] * (subtree[it]-1);
            }
        }
    }
    if(v > n)
    {
        ans -= siz(graph_tree[v]) * (tree_siz - subtree[v]) * (tree_siz - subtree[v]-1);
    }
    return subtree[v];
}


int main()
{
    //ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    //random_start();
    cin >> n >> m;
    if(n <= 2)
    {
        cout << "0\n";
        return 0;
    }
    rep(i,m)
    {
        int a,b;
        cin >> a >> b;
        graph[a].pb(b);
        graph[b].pb(a);
    }
    rep2(i,1,n) 
    {
        if(odw[i] == 0) 
        {
            tree_siz = 0;
            calc_pre(i,i);
            ans += tree_siz * (tree_siz-1) * (tree_siz-2);
            calc_comps(i,i);
            dfs_ans(i,i);
        }
    }
    
    cout << ans << "\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