Submission #402530

#	Time	Username	Problem	Language	Result	Execution time	Memory
402530		JerryLiu06	Making Friends on Joitter is Fun (JOI20_joitter2)	C++17	100 / 100	1298 ms	95732 KiB

joitter2

#include <bits/stdc++.h>
 
using namespace std;
 
using ll = long long;
using db = long double;
using str = string;
 
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;
 
using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>;
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;
 
#define mp make_pair
#define f first
#define s second

#define sz(x) (int)(x).size()
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define sor(x) sort(all(x))
#define ft front()
#define bk back()
#define pb push_back
#define pf push_front
 
#define lb lower_bound
#define ub upper_bound
 
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define R0F(i, a) ROF(i, 0, a)
#define EACH(a, x) for (auto& a : x)

const int MOD = 1e9 + 7;
const int MX = 1e5 + 10;
const ll INF = 1e18;

int N, M; ll ans; int par[MX], sz[MX]; queue<pi> todo;

unordered_set<int> ext[MX], adj[MX], radj[MX];

int dsu_sz(int A) { return sz(ext[A]) + sz(adj[A]) + sz(radj[A]); }

int find(int A) { return (par[A] == A ? A : (par[A] = find(par[A]))); }

void connect(int A, int B) {
    adj[A].insert(B); radj[B].insert(A);

    if (adj[B].count(A)) todo.push({A, B});
}
void onion(int A, int B) {
    if (A == B) return ; if (dsu_sz(A) < dsu_sz(B)) swap(A, B);

    ans += 1LL * sz[B] * sz(ext[A]) + 1LL * sz[A] * sz(ext[B]);

    par[B] = A; sz[A] += sz[B];

    EACH(C, ext[B]) { if (ext[A].count(C)) ans -= sz[A]; else ext[A].insert(C); }

    adj[A].erase(B); adj[B].erase(A); radj[A].erase(B); radj[B].erase(A);

    EACH(C, adj[B]) { radj[C].erase(B); connect(A, C); }
    EACH(C, radj[B]) { adj[C].erase(B); connect(C, A); }
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);

    cin >> N >> M; FOR(i, 1, N + 1) par[i] = i, sz[i] = 1, ext[i].insert(i);

    F0R(i, M) {
        int A, B; cin >> A >> B; B = find(B);

        if (find(A) != B && !ext[B].count(A)) {
            ext[B].insert(A); ans += sz[B]; 

            A = find(A); connect(A, B);

            while (!todo.empty()) {
                pi cur = todo.front(); todo.pop();

                onion(find(cur.f), find(cur.s));
            }
        }
        cout << ans << "\n";
    }
}

Compilation message (stderr)

joitter2.cpp: In function 'void onion(int, int)':
joitter2.cpp:62:5: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   62 |     if (A == B) return ; if (dsu_sz(A) < dsu_sz(B)) swap(A, B);
      |     ^~
joitter2.cpp:62:26: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   62 |     if (A == B) return ; if (dsu_sz(A) < dsu_sz(B)) swap(A, B);
      |                          ^~

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