Submission #430900

#	Time	Username	Problem	Language	Result	Execution time	Memory
430900		Kevin_Zhang_TW	Making Friends on Joitter is Fun (JOI20_joitter2)	C++17	17 / 100	5099 ms	114628 KiB

joitter2

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T> bool chmin(T &a, T b) { return b < a && (a = b, true); }
template<class T> bool chmax(T &a, T b) { return a < b && (a = b, true); }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() { cerr << endl; }
template<class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ', kout(b...); }
template<class T> void debug(T l, T r) { while (l != r) cerr << *l << " \n"[next(l)==r], ++l; }
#else
#define DE(...) 0
#define debug(...) 0
#endif
// My bug list :
// integer overflow
// 0based, 1based forgotten
// index out of bound
// n, m, i, j typo
// some cases are missing

const int MAX_N = 100010;

ll ans;

int n, m, g[MAX_N], sz[MAX_N];

unordered_set<int> in[MAX_N];

void init() {
	iota(g, g+n+1, 0);
	fill(sz, sz + n + 1, 1);
}

int F(int i) { return i == g[i] ? i : g[i] = F(g[i]); }

void clean(int a, int b) {
	vector<int> ina(AI(in[a]));
	for (int x : ina) {
		if (F(x) == F(b)) {
			in[a].erase(x);
			ans -= sz[ F(a) ];
		}
	}
}
void add_edge(int a, int b) {
	if (F(a) == F(b)) return;
	if (in[ F(b) ].count(a)) return;
	ans += sz[ F(b) ];
	in[F(b)].insert(a);

	bool mg = false;
	for (int x : in[ F(a) ]) if (F(x) == F(b)) {
		mg = true;
	}
	if (mg) {
		a = F(a), b = F(b);
		clean(a, b), clean(b, a);
		vector<int> nin(AI(in[a])); nin.insert(end(nin), AI(in[b]));

		ans -= 1ll * sz[a] * in[a].size() + 1ll * sz[b] * in[b].size();

		in[a].clear(), in[b].clear();

		ans += 2ll * sz[a] * sz[b];
		g[a] = b;
		sz[b] += sz[a];

		for (int i : nin) add_edge(i, a);
	}
}
int32_t main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	cin >> n >> m;
	init();
	while (m--) {
		int a, b;
		cin >> a >> b;
		add_edge(a, b);
		cout << ans << '\n';
   	}
}

• Subtask 1: 1 / 1
• Subtask 2: 16 / 16
• Subtask 3: 0 / 83