Submission #422594

#	Time	Username	Problem	Language	Result	Execution time	Memory
422594		Hideo	Making Friends on Joitter is Fun (JOI20_joitter2)	C++17	0 / 100	20 ms	30796 KiB

joitter2

#include <bits/stdc++.h>
using namespace std;

#define all(s) s.begin(), s.end()
#define ll long long
#define fr first
#define sc second
#define pb push_back
#define mk make_pair
#define pi pair < int, int >

const int N = 3e5 + 7;
const int INF = 1e9 + 7;

ll sum;
ll p[N];
int n, m;

set < int > g[N], q[N];

int findp (int x){
    if (p[x] < 0)
        return x;
    return p[x] = findp(p[x]);
}

bool check (int v, int u){
    v = findp(v);
    u = findp(u);
    if (v != u){
        for (auto to : g[u])
            if (findp(to) == v)
                return true;
    }
    return false;
}

void unite (int v, int u){
    v = findp(v);
    u = findp(u);
    if (v != u){
        sum -= 1ll * int(g[u].size()) * -p[u];
        sum -= 1ll * int(g[v].size()) * -p[v];
        if (g[u].size() > g[v].size())
            swap(v, u);
        for (auto to : g[u]){
            g[v].insert(to);
            q[findp(to)].erase(u);
            q[findp(to)].insert(v);
        }
        g[v].insert(u);
        g[v].erase(v);
        p[v] += p[u];
        p[u] = v;
        sum += 1ll * int(g[v].size()) * -p[v];
//        cout << v << ' ' << u << endl;
        vector < int > go;
        for (auto to : g[u]){
            if (q[v].find(findp(to)) != q[v].end()){
                go.pb(to);
            }
        }
        for (auto to : q[u]){
            if (q[to].find(v) != q[to].end()){
                go.pb(to);
            }
        }
        for (int to : go){
            unite(v, to);
        }
    }
}

main (){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    memset(p, -1, sizeof(p));
    cin >> n >> m;
    for (int i = 1; i <= m; i++){
        int a, b;
        cin >> a >> b;
        if (q[findp(b)].find(findp(a)) != q[findp(b)].end())
            unite(a, b);
        else {
            b = findp(b);
            sum -= 1ll * int(g[b].size()) * -p[b];
            g[b].insert(a);
            g[b].erase(b);
            a = findp(a);
            q[a].insert(b);
            sum += 1ll * int(g[b].size()) * -p[b];
        }
        cout << sum << endl;
    }
}

Compilation message (stderr)

joitter2.cpp:74:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   74 | main (){
      | ^~~~

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