Submission #2998759

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define rep(i, a) for (int (i) = 0; (i) < (int) (a); (i)++)
#define reps(i, a, b) for (int (i) = (int) (a); (i) < (int) (b); (i)++)
#define rrep(i, a) for (int (i) = (int) a-1; (i) >= 0; (i)--)
#define rreps(i, a, b) for (int (i) = (int) (a)-1; (i) >= (int) (b); (i)--)
#define MP(a, b) make_pair((a), (b))
#define PB(a) push_back((a))
#define all(v) (v).begin(), (v).end()
#define PRINT(f) if((f)){cout << (TRUE__) << endl;}else{cout << FALSE__ << endl;}
#define TRUE__ "Yes"
#define FALSE__ "No"
#define PERM(v) next_permutation(all(v))
#define UNIQUE(v) sort(all(v));(v).erase(unique(all(v)), v.end())
#define CIN(type, x) type x;cin >> x

#ifdef LOCAL
	#define lcout(a) cout << a;
	#define lcoutln(a) cout << a << endl;
	#define lcerr(a) cerr << a;
	#define lcerrln(a) cerr << a << endl;
#else
	#define lcout(a) 
	#define lcoutln(a) 
	#define lcerr(a) 
	#define lcerrln(a) 
#endif

class uni_find
{
public:
	vector<int> par;
	vector<int> rank;
	vector<int> hen;
	int mysize;
	uni_find(int n) {init(n);}
	void init(int n);
	int root(int x) {return par[x] == x ? x : par[x] = root(par[x]);}
	bool same(int x, int y) {return root(x) == root(y);}
	void unite(int x, int y);
	int size() {return mysize;}
};
void uni_find::init(int n)
{
	vector<int> pt(n);
	vector<int> rt(n);
	vector<int> ht(n);
	par = pt;
	rank = rt;
	hen = ht;
	rep(i, n) par[i] = i, rank[i] = 0, hen[i] = 0;
	mysize = n;
}
void uni_find::unite(int x, int y)
{
	x = root(x);
	y = root(y);
	if (x == y) {
		hen[x]++;
		return;
	}
	if (rank[x] < rank[y]) {
		par[x] = y;
		hen[y] += hen[x] + 1;
	}
	else {
		par[y] = x;
		hen[x] += hen[y] + 1;
		if (rank[x] == rank[y]) rank[x]++;
	}
}

int N, M;

int main()
{
	cin >> N >> M;
	uni_find uf(N);
	rep(i, M) {
		CIN(int, a);
		CIN(int, b);
		uf.unite(a-1, b-1);
	}
	int res = 0;
	vector<int> cnt(N);
	rep(i, N) cnt[uf.par[i]]++;
	rep(i, N) {
		if (i == uf.par[i]) {
			res += uf.hen[i] == cnt[i] - 1;
		}
	}
	cout << res << endl;
}

Submission Info

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