Submission #722027

#	Time	Username	Problem	Language	Result	Execution time	Memory
722027		fdnfksd	Mergers (JOI19_mergers)	C++14	100 / 100	1250 ms	206200 KiB

mergers

#include<bits/stdc++.h>
#define TASKNAME "codeforce"
#define pb push_back
#define pli pair<int,int>
#define fi first
#define se second
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL);
using namespace std;
using ll=long long;
const ll maxN=5e5+10;
const ll inf=1e18;
const ll mod=1e9+7;
ll P[maxN][21],h[maxN],in[maxN],out[maxN],tg=0;
vector<ll>g[maxN];
void dfs(ll u=1,ll p=1)
{
    P[u][0]=p;
    in[u]=++tg;
    for(int i=1;i<=20;i++) P[u][i]=P[P[u][i-1]][i-1];
    for(int v:g[u])
    {
        if(v!=p)
        {
            h[v]=h[u]+1;
            dfs(v,u);
        }
    }
}
ll cnt[maxN];
vector<ll>adj[maxN];
void dfs1(ll u=1,ll p=0)
{
    for(int v:g[u])
    {
        if(v!=p)
        {
            dfs1(v,u);
            cnt[u]+=cnt[v];
        }
    }
}
void dfs2(ll u=1,ll p=0,ll last=-1)
{
    if(cnt[u]==0&&last!=-1)
    {
        adj[u].pb(last);
        adj[last].pb(u);
    }
    if(cnt[u]==0) last=u;
    for(int v:g[u])
    {
        if(v!=p)
        {
            dfs2(v,u,last);
        }
    }
}
ll n,k;
vector<ll>vec[maxN];
bool cmp(ll x,ll y)
{
    return in[x]<in[y];
}
ll lca(ll u,ll v)
{
    if(h[u]<h[v]) swap(u,v);
    for(int i=20;i>=0;i--) if(h[u]-(1<<i)>=h[v]) u=P[u][i];
    if(u==v) return u;
    for(int i=20;i>=0;i--) if(P[u][i]!=P[v][i]) u=P[u][i],v=P[v][i];
    return P[u][0];
}
void solve()
{
    cin >> n >> k;
    for(int i=1;i<n;i++)
    {
        ll u,v;
        cin >> u >> v;
        g[u].pb(v);
        g[v].pb(u);
    }
    dfs();
    for(int i=1;i<=n;i++)
    {
        ll x;
        cin >> x;
        vec[x].pb(i);
    }
    for(int i=1;i<=k;i++)
    {
        sort(vec[i].begin(),vec[i].end(),cmp);
        for(int j=0;j<vec[i].size();j++)
        {
            cnt[vec[i][j]]++;
            cnt[lca(vec[i][j],vec[i][(j+1)%vec[i].size()])]--;
        }
    }
    dfs1();
    dfs2();
    ll ct=0;
    for(int i=1;i<=n;i++)
    {
        if(adj[i].size()==1) ct++;
    }
    cout <<(ct+1)/2;
}
int main()
{
    fastio
    //freopen(TASKNAME".INP","r",stdin);
    //freopen(TASKNAME".OUT","w",stdout);
    solve();
}

Compilation message (stderr)

mergers.cpp: In function 'void solve()':
mergers.cpp:92:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   92 |         for(int j=0;j<vec[i].size();j++)
      |                     ~^~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 24 / 24
• Subtask 3: 14 / 14
• Subtask 4: 22 / 22
• Subtask 5: 30 / 30