제출 #51911

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
51911		pzdba	철인 이종 경기 (APIO18_duathlon)	C++14	0 / 100	281 ms	43108 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long LL;

vector<pii> g[100005];
set<int> gs[100005];
bool idx[200005];
int low[100005], vis[100005], p[100005], sz[100005], T = 1;
void dfs1(int u, int p){
	vis[u] = low[u] = T++;
	for(int i=0;i<g[u].size();i++){
		int v = g[u][i].first;
		if(v == p) continue;
		if(vis[v]) low[u] = min(low[u], vis[v]);
		else{
			dfs1(v, u);
			low[u] = min(low[u], low[v]);
			if(low[v] > vis[u]) idx[g[u][i].second] = 1;
		}
	}
}

int root(int a){
	while(p[a] != a){
		p[a] = p[p[a]];
		a = p[a];
	}
	return a;
}
bool merge(int a, int b){
	a = root(a), b = root(b);
	if(a == b) return 0;
	sz[b] += sz[a];
	p[a] = b;
	return 1;
}

LL s[100005], sc[100005];
LL ans = 0;

void dfs2(int u, int p){
	for(set<int>::iterator its=gs[u].begin();its != gs[u].end();its++){
		int v = *its;
		if(v == p) continue;
		dfs2(v, u);

		ans += (LL)sc[v]*sz[u]; // f
		if(sz[u] > 1) ans += (LL)s[v]*(sz[u]-1 + (LL)(sz[u]-1)*(sz[u]-2)); // cf

		ans += (LL)sc[v]*s[u]; // f
		ans += (LL)s[v]*sc[u]; // cf

		s[u] += s[v];
		sc[u] += sc[v];
		sc[u] += (LL)s[v]*sz[u];
	}
	s[u] += sz[u];
	sc[u] += (LL)sz[u]*(sz[u]-1);
}

int main(){
	int n, m;
	scanf("%d%d", &n, &m);
	for(int i=0;i<m;i++){
		int a, b;
		scanf("%d%d", &a, &b);
		g[a].push_back(pii(b, i));
		g[b].push_back(pii(a, i));
	}
	dfs1(1, 0);
	for(int i=1;i<=n;i++) p[i] = i, sz[i] = 1;
	for(int i=1;i<=n;i++){
		for(int j=0;j<g[i].size();j++){
			int v = g[i][j].first, edge = g[i][j].second;
			if(!idx[edge]){
				merge(i, v);
			}
		}
	}
	int r = 0;
	for(int i=1;i<=n;i++){
		for(int j=0;j<g[i].size();j++){
			int v = g[i][j].first, edge = g[i][j].second;
			if(!idx[edge]) continue;
			if(root(i) == root(v)) continue; 
			gs[root(i)].insert(root(v));
			gs[root(v)].insert(root(i));
		}
		if(root(i) == i){
			r = i;
		}
	}
	dfs2(r, 0);
	ans *= 2;
	for(int i=1;i<=n;i++){
		if(root(i) == i){
			ans += (LL)sz[i]*(sz[i]-1)*(sz[i]-2);
		}
	}
	printf("%lld\n", ans);
}

컴파일 시 표준 에러 (stderr) 메시지

count_triplets.cpp: In function 'void dfs1(int, int)':
count_triplets.cpp:12:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<g[u].size();i++){
              ~^~~~~~~~~~~~
count_triplets.cpp: In function 'int main()':
count_triplets.cpp:74:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<g[i].size();j++){
               ~^~~~~~~~~~~~
count_triplets.cpp:83:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<g[i].size();j++){
               ~^~~~~~~~~~~~
count_triplets.cpp:64:7: 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:67:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &a, &b);
   ~~~~~^~~~~~~~~~~~~~~~

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