제출 #1195900

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1195900		vnedu	전압 (JOI14_voltage)	C++17	100 / 100	99 ms	18248 KiB

voltage

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

template<class T> bool maximize(T &a, const T &b){ return (a < b ? a = b, 1 : 0); }
template<class T> bool minimize(T &a, const T &b){ return (a > b ? a = b, 1 : 0); }

#define fi first
#define se second

#define pb push_back
#define ii pair<int, int>

#define all(x) x.begin(), x.end()

#define TASK "nonsense"

/// end of template ///

const int N = 1e5 + 10;
const int M = 2e5 + 10;
int n,m;
ii edge[M];
namespace subfull
{
    vector<ii> adj[N];
    int dep[N],parId[N],sum[N][2],num[2],pass[M][2];
    void dfs(int u)
    {
        for(ii p : adj[u]) if(dep[p.fi]==-1)
        {
//            cout<<u<<' '<<p.fi<<'\n';
            dep[p.fi]=dep[u]+1;
            parId[p.fi]=p.se;
            dfs(p.fi);
        }
    }
    void work(int u)
    {
        for(ii p : adj[u]) if(parId[p.fi]==p.se)
        {
            work(p.fi);
            for(int j=0;j<2;++j) sum[u][j]+=sum[p.fi][j];
        }
        if(parId[u]!=-1)
        {
            pass[parId[u]][0]=sum[u][0];
            pass[parId[u]][1]=sum[u][1];
        }
    }
    void solve()
    {
        for(int i=1;i<=m;++i)
        {
            adj[edge[i].fi].pb({edge[i].se,i});
            adj[edge[i].se].pb({edge[i].fi,i});
        }
        memset(dep,-1,sizeof(dep));
        memset(parId,-1,sizeof(parId));
        for(int i=1;i<=n;++i) if(dep[i]==-1)
        {
            dep[i]=1;
            dfs(i);
        }
        for(int i=1;i<=m;++i)
        {
            int u=edge[i].fi,v=edge[i].se;
            if(dep[u]>dep[v]) swap(u,v);
            if(parId[v]!=i)
            {
                bool con=((dep[u]&1)!=(dep[v]&1));
                ++sum[v][con];
                --sum[u][con];
                ++num[con];
                ++pass[i][con];
            }
        }
        for(int i=1;i<=n;++i) if(dep[i]==1) work(i);
        int ans=0;
        for(int i=1;i<=m;++i) if((pass[i][0]==num[0]) && pass[i][1]==0) ++ans;
        cout<<ans;
    }
}
void solve()
{
    cin>>n>>m;
    for(int i=1;i<=m;++i) cin>>edge[i].fi>>edge[i].se;
    return void(subfull::solve());
}
int main()  {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

//    freopen(TASK".inp","r",stdin);
//    freopen(TASK".out","w",stdout);

    int testcase=1;
//    cin>>testcase;

    while (testcase--)
        solve();

    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 35 / 35
• Subtask 4: 45 / 45