Submission #218272

#	Time	Username	Problem	Language	Result	Execution time	Memory
218272		VEGAnn	Duathlon (APIO18_duathlon)	C++14	31 / 100	232 ms	34668 KiB

count_triplets

#include <stdio.h>
#include <vector>
#include <set>
using namespace std;
typedef long long ll;

int N,M,X[200200],Y[200200],P[200200]; bool chk[300300];
vector<int> G[100100],V[300300];
int dep[200200],low[200200];
int sz[300300],ho[300300], siz[300300];

int find(int x)
{
	if (P[x] != x) P[x] = find(P[x]);
	return P[x];
}

void go(int x, int l)
{
	low[x] = dep[x];
	chk[x] = 1;
	for (auto &i : G[x]) if (i != l){
		int y = (x == X[i] ? Y[i] : X[i]);
		if (!chk[y]){
			dep[y] = dep[x] + 1;
			go(y,i);
			if (dep[x] > low[y]){
				if (l != -1) P[find(l)] = find(i);
			}
			if (low[x] > low[y])
				low[x] = low[y];
		}
		else if (dep[x] > dep[y]){
			if (l != -1) P[find(l)] = find(i);
			if (low[x] > dep[y]){
				low[x] = dep[y];
			}
		}
	}
}

vector<int> comp;
void gather(int x, int l)
{
	comp.push_back(x);
	chk[x] = 1;
	siz[x] = sz[x];
	for (auto &y : V[x]) if (y != l){
		gather(y,x);
		siz[x] += siz[y];
	}
}

long long ans;
void bye(int v, int p, int c){
    ans += ll(sz[v]) * (ll(sz[v]) - 1ll) * (ll(sz[v]) - 2ll) / 2ll; // first

    ans += (c - ll(sz[v])) * (ll(sz[v]) - 1ll) * (ll(sz[v]));

    ll sum = 0ll;

    for (int u : V[v]){

//        if (v < N)
//            ans += (ll(sz[v]) * ll(sz[u]) * (ll(sz[u]) - 1ll)) / 2ll;

        if (v >= N){
            if (u != p){
                ll cur = c - siz[u] - sz[v];

                ans += (cur * ll(sz[v]));
            } else {
                ll cur = siz[v] - sz[v];

                ans += (cur * ll(sz[v]));
            }
        }

        if (u != p) {
            bye(u, v, c);
            ans += sum * ll(siz[u]) * ll(sz[v]);
            sum += ll(siz[u]);
        } else {
            ans += sum * (c - ll(siz[v])) * ll(sz[v]);
            sum += (c - ll(siz[v]));
        }

        ans += ll(sz[v]) * (ll(sz[v]) - 1) * ll(sz[u]) / 2ll; //new

    }
}

int main(){

//    freopen("in.txt","r",stdin);

	scanf ("%d %d",&N,&M);
	for (int i=0;i<M;i++){
		scanf ("%d %d",&X[i],&Y[i]);
		X[i]--; Y[i]--;
		G[X[i]].push_back(i);
		G[Y[i]].push_back(i);
		P[i] = i;
	}

	for (int i=0;i<N;i++) if (!chk[i]) go(i,-1);

	for (int i=0;i<N;i++){
		set<int> s;
		for (auto &e : G[i]){
			s.insert(find(e));
		}

		if (s.size() == 1) sz[N+*s.begin()]++;
		else{
			sz[i] = 1;
			for (auto &e : s){
				V[i].push_back(N+e);
				V[N+e].push_back(i);
			}
		}
	}
	for (int i=0;i<N+M;i++) chk[i] = 0;

	for (int i=0;i<N+M;i++) if (!chk[i]){
		comp.clear();
		gather(i,-1);
		int C = 0;
		for (auto &x : comp) C += sz[x];
		for (auto &x : comp){
			ho[x] = sz[x];
			for (auto &y : V[x]) ho[x] += sz[y];
		}

//		ans += (long long) C * (C - 1) * (C - 2);

		bye(i,-1,C);
	}

	printf ("%lld\n",ans * 2);

	return 0;
}

Compilation message (stderr)

count_triplets.cpp: In function 'int main()':
count_triplets.cpp:97:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf ("%d %d",&N,&M);
  ~~~~~~^~~~~~~~~~~~~~~
count_triplets.cpp:99:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf ("%d %d",&X[i],&Y[i]);
   ~~~~~~^~~~~~~~~~~~~~~~~~~~~

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