Submission #42428

#	Time	Username	Problem	Language	Result	Execution time	Memory
42428		dqhungdl	우호 조약 체결 (JOI14_friends)	C++14	100 / 100	121 ms	69420 KiB

friends

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

int64_t n,m,res=0,P[100005],Size[100005];
bool Free[100005];
vector<int64_t> V,g[100005];

int64_t Find(int64_t u)
{
    if(u==P[u])
        return u;
    return P[u]=Find(P[u]);
}

void Union(int64_t u,int64_t v)
{
    if(Size[u]<Size[v])
        swap(u,v);
    P[v]=u;
    Size[u]+=Size[v];
}

void DFS(int64_t u)
{
    for(int64_t i=0;i<g[u].size();i++)
    {
        V.push_back(g[u][i]);
        if(Free[g[u][i]]==false)
        {
            Free[g[u][i]]=true;
            DFS(g[u][i]);
        }
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    //freopen("TEST.INP","r",stdin);
    cin>>n>>m;
    int64_t u,v;
    while(m--)
    {
        cin>>u>>v;
        g[u].push_back(v);
    }
    for(int64_t i=1;i<=n;i++)
    {
        P[i]=i;
        Size[i]=1;
    }
    for(int64_t i=1;i<=n;i++)
        if(Free[i]==false&&g[i].size()>=2)
        {
            V.clear();
            DFS(i);
            for(int64_t j=1;j<V.size();j++)
            {
                int64_t u=Find(V[0]);
                int64_t v=Find(V[j]);
                if(u!=v)
                    Union(u,v);
            }
        }
    for(int64_t i=1;i<=n;i++)
        if(P[i]==i)
        {
            if(Size[i]>1)
                res+=Size[i]*(Size[i]-1);
            else
                res+=g[i].size();
        }
    cout<<res;
}

Compilation message (stderr)

friends.cpp: In function 'void DFS(int64_t)':
friends.cpp:25:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int64_t i=0;i<g[u].size();i++)
                      ^
friends.cpp: In function 'int main()':
friends.cpp:57:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int64_t j=1;j<V.size();j++)
                              ^

• Subtask 1: 5 / 5
• Subtask 2: 30 / 30
• Subtask 3: 65 / 65