Submission #422563

#	Time	Username	Problem	Language	Result	Execution time	Memory
422563		Hideo	Making Friends on Joitter is Fun (JOI20_joitter2)	C++17	Compilation error	0 ms	0 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);
        }
        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;
        for (auto to : g[v]){
            if (check(v, to)){
                unite(v, to);
            }
        }
    }
}

main (){
a    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.end())
        if (check(b, a))
            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:63:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   63 | main (){
      | ^~~~
joitter2.cpp: In function 'int main()':
joitter2.cpp:64:1: error: 'a' was not declared in this scope
   64 | a    memset(p, -1, sizeof(p));
      | ^