제출 #104956

#제출 시각아이디문제언어결과실행 시간메모리
104956puyu_liaoDuathlon (APIO18_duathlon)C++14
23 / 100
155 ms17784 KiB
#include<bits/stdc++.h>
#include<stdint.h>
using namespace std;
#define IOS {cin.tie(0);ios_base::sync_with_stdio(false);}
#define N 300005
#define int int64_t
 
vector<int> v[N];
int sz[N];
int ans = 0;
bitset<N> vis,rt;
 
void dfs(int x,int p){
	vis[x] = 1;
	sz[x] = 1;
	for(int i : v[x]) if(i != p){
		if(vis[i]) exit(-1);
		dfs(i,x);
		sz[x] += sz[i];
	}
}
 
void dfs2(int x, int p, int sum) {
	for(int i : v[x]) {
		if(i != p) dfs2(i, x, sum), ans += sz[i] * (sum - sz[i] - 1);
		else ans += (sum - sz[x]) * (sz[x] - 1);
	}
}
 
int32_t main(){
	IOS;
	int n,m,a,b;
	cin >> n >> m;
	for(int i=0;i<m;i++){
		cin >> a >> b;
		v[a].push_back(b);
		v[b].push_back(a);
	}
	//if(m!=n-1) return 0;
	for(int i=1;i<=n;i++) if(!vis[i]){
		rt[i] = 1;
		dfs(i,i);
	}
	//for(int i=1;i<=n;i++) cout << sz[i] << '\n';
	for(int i=1;i<=n;i++) if(rt[i]){
		dfs2(i,i,sz[i]);
	}
	cout << ans << '\n';
	return 0;
}
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