Submission #52631323

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
void debug_out() { cerr << endl; }
template<class T> ostream& prnt(ostream& out, T v) { out << v.size() << '\n'; for(auto e : v) out << e << ' '; return out;}
template<class T> ostream& operator<<(ostream& out, vector <T> v) { return prnt(out, v); }
template<class T> ostream& operator<<(ostream& out, set <T> v) { return prnt(out, v); }
template<class T1, class T2> ostream& operator<<(ostream& out, map <T1, T2> v) { return prnt(out, v); }
template<class T1, class T2> ostream& operator<<(ostream& out, pair<T1, T2> p) { return out << '(' << p.first << ' ' << p.second << ')'; }
template <typename Head, typename... Tail> void debug_out(Head H, Tail... T) { cerr << " " << H; debug_out(T...);}
#define dbg(...) cerr << #__VA_ARGS__ << " ->", debug_out(__VA_ARGS__)
#define dbg_v(x, n) do{cerr<<#x"[]: ";for(int _=0;_<n;++_)cerr<<x[_]<<" ";cerr<<'\n';}while(0)
#define dbg_ok cerr<<"OK!\n"
#define ll long long
#define ld long double
#define ull unsigned long long
#define pii pair<int,int>
#define MOD 1000000007
#define zeros(x) x&(x-1)^x
#define fi first
#define se second

const long double PI = acos(-1);

ll n, m;
bool vis[200005];
vector<int> v[200005];

ll dfs(int x) {
	vis[x] = true;
	ll all = 1;
	for (auto i : v[x]) {
		if (vis[i]) continue;
		all += dfs(i);
	}
	return all;
}

int main()
{
   ios::sync_with_stdio(false);

   cin >> n >> m;
	for (int i = 0; i < m; i++) {
		int x, y;
		cin >> x >> y;
		v[x].push_back(y);
		v[y].push_back(x);
	}

	ll total = -m;
	for (int i = 0; i < n; i++) {
		if (!vis[i]) {
			ll sz = dfs(i);
			total += sz * (sz - 1) / 2;
		}
	}

	cout << total;

   return 0;
}

Submission Info

Judge Result