Submission #1108296

#	Time	Username	Problem	Language	Result	Execution time	Memory
1108296		sitablechair	Making Friends on Joitter is Fun (JOI20_joitter2)	C++17	0 / 100	2 ms	9808 KiB

joitter2

#include <bits/stdc++.h>

#define ll long long
#define ldb long double
#define endl '\n'
#define For(i,l,r) for(int i=l;i<=r;i++)
#define ForD(i,r,l) for(int i=r;i>=l;i--)
#define REP(i,l,r) For(i,l,r-1)
#define PER(i,r,l) ForD(i,r-1,l)
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
#define All(x,n) x+1,x+1+n
#define Alll(x,n) x,x+n
#define sz(x) (signed)x.size()
#define unq(x) x.resize(unique(all(x))-x.begin())
#define mpa make_pair

#ifdef NCGM
#include"debug.h"
#else 
#define debug(...) "fr";
#endif

using namespace std;

const int N=1e5+3;

int f[N],n,m;
set<int> st[N],st1[N];
map<pair<int,int>,bool> sus;
ll ans=0;

int find_set(int u) {
    return (f[u]<0?u:f[u]=find_set(f[u]));
}
void unite(int u,int v) {
    int a=find_set(u),b=find_set(v);
    if (a==b) return;
    if (st[a]<st[b]) swap(a,b);
    ans+=1LL*sz(st1[a])*f[a];
    ans+=1LL*sz(st1[b])*f[b];
    ans-=1LL*f[a]*(f[a]-1);
    ans-=1LL*f[b]*(f[b]-1);
    for(auto el: st[b]) {
        if (st1[a].find(el)!=st1[a].end()) st1[a].erase(el);
        st[a].insert(el);
    }
    st[b].clear();
    for(auto el: st1[b])
        if (st[a].find(el)==st[a].end()) st1[a].insert(el);
    st1[b].clear();
    f[a]+=f[b];
    f[b]=a;
    ans+=1LL*f[a]*(f[a]-1);
    ans-=1LL*f[a]*sz(st1[a]);
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin >> n >> m;
    For(i,1,n) {
        f[i]=-1;
        st[i].insert(i);
    }
    For(i,1,m) {
        int u,v;
        cin >> u >> v;
        if (sus[{v,u}]) unite(u,v);
        else {
            if (st1[find_set(v)].find(u)==st1[find_set(v)].end()) { 
                st1[find_set(v)].insert(u);
                ans++;
            }
        }
        sus[{u,v}]=1;
        cout << ans << endl;
    }
    return 0;
}

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