Submission #287549

#	Time	Username	Problem	Language	Result	Execution time	Memory
287549		ACmachine	Duathlon (APIO18_duathlon)	C++17	0 / 100	343 ms	35500 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using ordered_map = tree<T, U, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

typedef long long ll;
typedef long double ld;
typedef double db;
typedef string str;

typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pii> vpii;
typedef vector<pll> vpll;
typedef vector<str> vstr;

#define FOR(i,j,k,in) for(int i=(j); i < (k);i+=in)
#define FORD(i,j,k,in) for(int i=(j); i >=(k);i-=in)
#define REP(i,b) FOR(i,0,b,1)
#define REPD(i,b) FORD(i,b,0,1)
#define pb push_back 
#define mp make_pair
#define ff first
#define ss second
#define all(x) begin(x), end(x)
#define rsz resize 

const double EPS = 1e-9;
const int MOD = 1e9+7; // 998244353;
const ll INFF = 1e18;
const int INF = 1e9;
const ld PI = acos((ld)-1);
const vi dy = {1, 0, -1, 0, -1, 1, 1, -1};
const vi dx = {0, 1, 0, -1, -1, 1, -1, 1};

#ifdef DEBUG
#define DBG if(1)
#else
#define DBG if(0)
#endif

#define dbg(x) cout << "(" << #x << " : " << x << ")" << endl;
// ostreams
template <class T, class U>
ostream& operator<<(ostream& out, const pair<T, U> &par) {out << "[" << par.first << ";" << par.second << "]"; return out;}
template <class T>
ostream& operator<<(ostream& out, const set<T> &cont) { out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template <class T, class U>
ostream& operator<<(ostream& out, const map<T, U> &cont) {out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template<class T>
ostream& operator<<(ostream& out, const vector<T> &v){ out << "[";  REP(i, v.size()) out << v[i] << ", ";  out << "]"; return out;}
// istreams
template<class T>
istream& operator>>(istream& in, vector<T> &v){ for(auto &x : v) in >> x; return in; }
template<class T, class U>
istream& operator>>(istream& in, pair<T, U> &p){ in >> p.ff >> p.ss; return in; }
//searches
template<typename T, typename U>
T bsl(T lo, T hi, U f){ hi++; T mid; while(lo < hi){ mid = (lo + hi)/2; f(mid) ? hi = mid : lo = mid+1; } return lo; }
template<typename U>
double bsld(double lo, double hi, U f, double p = 1e-9){ int r = 3 + (int)log2((hi - lo)/p); double mid; while(r--){ mid = (lo + hi)/2; f(mid) ? hi = mid : lo = mid; } return (lo + hi)/2; }
template<typename T, typename U>
T bsh(T lo, T hi, U f){ lo--; T mid; while(lo < hi){ mid = (lo + hi + 1)/2; f(mid) ? lo = mid : hi = mid-1; } return lo; }
template<typename U>
double bshd(double lo, double hi, U f, double p = 1e-9){ int r = 3+(int)log2((hi - lo)/p); double mid; while(r--){ mid = (lo + hi)/2; f(mid) ? lo = mid : hi = mid; } return (lo + hi)/2; }
// some more utility functions
template<typename T>
pair<T, int> get_min(vector<T> &v){ typename vector<T> :: iterator it = min_element(v.begin(), v.end()); return mp(*it, it - v.begin());}
template<typename T>
pair<T, int> get_max(vector<T> &v){ typename vector<T> :: iterator it = max_element(v.begin(), v.end()); return mp(*it, it - v.begin());}        
template<typename T> bool ckmin(T& a, const T& b){return b < a ? a = b , true : false;}
template<typename T> bool ckmax(T& a, const T& b){return b > a ? a = b, true : false;}

// centroid decomposition of a biconnected component tree dafuq
// first only centoid decomp to pass those subtasks

template<typename T>
struct edge{
    int src;
    int dest;
    T cost;
};
template<typename T>
class graph{
    public: 
    vector<edge<T>> edges;
    vector<vector<int>> adj;
    int n;
    graph(){};
    graph(int _n){
        n = _n;
        adj.resize(n);
    }
};

template<typename T>
class undigraph : public graph<T>{
    public:
        using graph<T>::edges;
        using graph<T>::adj;
        using graph<T>::n;
        undigraph() : graph<T>(){};
        undigraph(int _n) : graph<T>(_n){};

        int add_edge(int src, int dest, T cost = 1){
            int id = edges.size();
            edges.push_back({src, dest, cost});
            adj[src].push_back(id);
            adj[dest].push_back(id);
            return id;
        }
};
struct bcc_decomposition{
    graph<int> g; 
    vi bcc;
    vi low, in;
    vector<bool> isbridge;
    int t = 0;
    vi sz;
    void init(){
        bcc.resize(g.n, -1);
        low.resize(g.n); in.resize(g.n, -1);
        isbridge.resize(g.edges.size(), false);
        sz.rsz(g.n, 0);
    }
    void get_bridges(int v, int p){
        in[v] = t++;
        low[v] = INF;
        for(int id : g.adj[v]){
            edge<int> e = g.edges[id];
            int other = e.src ^ e.dest ^ v;
            if(other == p) continue;
            if(in[other] == -1){
                get_bridges(other, v);
                if(low[other] > in[v]){
                    isbridge[id] = true;
                }
                low[v] = min(low[v], low[other]);
            }
            else if(in[v] > in[other]){
                low[v] = min(low[v], in[other]);
            }
        }
    }
    int cnt = 0;
    void decompose(){
        REP(i, g.n){
            if(in[i] == -1) get_bridges(i, -1);
        }
        function<void(int)> dfs = [&](int v){
            bcc[v] = cnt;
            for(int id : g.adj[v]){
                if(isbridge[id]) continue;
                edge<int> e = g.edges[id];
                int other = e.src ^ e.dest ^ v;
                if(bcc[other] == -1) dfs(other);
            }
        };
        REP(i, g.n){
            if(bcc[i] == -1){
                dfs(i);
                ++cnt;
            }
        }
        REP(i, g.n) sz[bcc[i]]++;
    }
};
struct AcAutomaton{
    int n, m;
    undigraph<int> g2;
    undigraph<int> g;
    bcc_decomposition bccd;
	void read_in(){
		cin >> n >> m;
        g2 = undigraph<int>(n);
        REP(i, m){
            pii e; cin >> e;
            e.ff--; e.ss--;
            g2.add_edge(e.ff, e.ss);
        }
	}
    ll ans = 0;
    vi sz;
    vi roots;
    void get_sz(){
        sz.resize(g.n);
        vector<bool> visited(g.n, false);
        function<void(int, int)> dfs = [&](int v, int p){
            sz[v] = bccd.sz[v];
            visited[v] = true;
            for(int id : g.adj[v]){
                edge<int> e = g.edges[id];
                int other = e.src ^ e.dest ^ v;
                if(other != p){
                    dfs(other, v);
                    sz[v] += sz[other];
                }
            }
        };
        REP(i, g.n){
            if(!visited[i]){
                roots.pb(i);
                dfs(i, -1);
            }
        }
    }
    void reroot(int v, int p){
        if(p != -1){
            sz[p] -= sz[v];
            sz[v] += sz[p];
        }
        // process;
        vll children;
        for(int id : g.adj[v]){
            edge<int> e = g.edges[id];
            int other = e.src ^ e.dest ^ v;
            children.pb(sz[other]);
        }
        for(ll x : children){
            ans -= ((ll)bccd.sz[v] - 1)*(x + 1)*x;
            ans -= x*(x-1);
        }
        children.clear();
        for(int id : g.adj[v]){
            edge<int> e = g.edges[id];
            int other = e.src ^ e.dest ^ v;
            if(other != p) reroot(other, v);
        }
        if(p != -1){
            sz[v] -= sz[p];
            sz[p] += sz[v];
        }
    }
	void solve(){
        ans += ((ll)g2.n * ((ll)g2.n -1) * ((ll)g2.n-2));
        bccd.g = g2;
        bccd.init();
        bccd.decompose();
        g = undigraph<int> (bccd.cnt);
        set<int> added;
        REP(i, g2.n){
            for(int id : g2.adj[i]){
                edge<int> e = g2.edges[id];
                int other = e.src ^ e.dest ^ i;
                if(bccd.bcc[i] == bccd.bcc[other]) continue;
                if(added.find(id) != added.end()) continue;
                added.insert(id);
                g.add_edge(bccd.bcc[i], bccd.bcc[other]); 
            }
        }
        get_sz();
        for(auto x : roots) reroot(x, -1); 
		cout << ans << endl;
	}
};
    
int main(){
 	ios_base::sync_with_stdio(false);
 	cin.tie(NULL); cout.tie(NULL);
	int tcase = 1;
	while(tcase--){
		AcAutomaton solver;
		solver.read_in();
		solver.solve();
	}
    return 0;
}

• 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