Submission #509906

#	Time	Username	Problem	Language	Result	Execution time	Memory
509906		leinad2	Making Friends on Joitter is Fun (JOI20_joitter2)	C++17	0 / 100	3 ms	4940 KiB

joitter2

#include<bits/stdc++.h>
using namespace std;
int n, m, i, j, k, a, b, sz[100010], indeg[100010], par[100010];
long long ans;
int Find(int v){return v==par[v]?v:par[v]=Find(par[v]);}
map<int, set<int> >adj[100010];
main()
{
    scanf("%d %d", &n, &m);
    for(i=0;i++<n;)sz[i]=1,par[i]=i;
    while(m--)
    {
        scanf("%d %d", &a, &b);
        int x=a, y=b;
        a=Find(a);b=Find(b);
        if(a!=b)
        {
            if(adj[a].find(b)==adj[a].end())
            {
                if(adj[b][a].find(x)==adj[b][a].end())
                {
                    adj[b][a].insert(x);
                    ans+=sz[b];
                    indeg[b]++;
                }
            }
            else
            {
                ans-=1LL*(indeg[a]-(int)adj[a][b].size())*sz[a];
                ans-=1LL*(indeg[b])*sz[b];
                ans+=1LL*sz[a]*sz[b];
                ans+=1LL*(sz[b]-adj[a][b].size())*sz[a];
                if(indeg[a]<indeg[b])swap(adj[a], adj[b]);
                for(auto p:adj[b])
                {
                    for(auto q:p.second)
                    adj[a][p.first].insert(q);
                }
                adj[b].clear();
                indeg[a]-=adj[a][b].size();
                adj[a].erase(b);
                sz[a]+=sz[b];
                indeg[a]+=indeg[b];
                par[b]=a;
                ans+=1LL*indeg[a]*sz[a];
            }
        }
        printf("%lld\n", ans);
    }
}

Compilation message (stderr)

joitter2.cpp:7:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    7 | main()
      | ^~~~
joitter2.cpp: In function 'int main()':
joitter2.cpp:14:18: warning: unused variable 'y' [-Wunused-variable]
   14 |         int x=a, y=b;
      |                  ^
joitter2.cpp:9:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
    9 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
joitter2.cpp:13:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |         scanf("%d %d", &a, &b);
      |         ~~~~~^~~~~~~~~~~~~~~~~

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