Submission #564816

#	Time	Username	Problem	Language	Result	Execution time	Memory
564816		urosk	Mergers (JOI19_mergers)	C++14	100 / 100	2796 ms	250316 KiB

mergers

// __builtin_popcount(x)
// __builtin_popcountll(x)
#define here cerr<<"===========================================\n"
#include <bits/stdc++.h>
#define ld double
#define ll long long
#define ull unsigned long long
#define llinf 100000000000000000LL // 10^17
#define iinf 2000000000 // 2*10^9
#define pb push_back
#define popb pop_back
#define fi first
#define sc second
#define endl '\n'
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pld pair<ld,ld>
#define sz(a) int(a.size())
#define all(a) a.begin(),a.end()
#define ceri(a,l,r) {for(ll i_ = l;i_<=r;i_++) cerr<<a[i_]<< " ";cerr<<endl;}
using namespace std;

#define maxn 500005
ll n,k;
vector<ll> g[maxn];
vector<ll> v;
ll a[maxn];
ll in[maxn];
ll out[maxn];
ll dp[maxn][3];
ll b[maxn][3];
ll it = 1;
void dfs(ll u,ll par){
    in[u] = it++;
    for(ll s : g[u]){
        if(s==par) continue;
        dfs(s,u);
    }
    out[u] = it-1;
}
bool intree(ll x,ll i){
    return x>=in[i]&&out[i]>=x;
}
bool bio[maxn];
ll ans = 0;
set<ll> rg[maxn];
ll dsu[maxn];
ll root(ll x){
    while(x!=dsu[x]){
        dsu[x] = dsu[dsu[x]];
        x = dsu[x];
    }
    return x;
}
void upd(ll x,ll y){
    x = root(x);
    y = root(y);
    dsu[x] = y;
}
map<pll,bool> mp;
void dfs2(ll u,ll par){
    dp[u][1] = b[a[u]][1];
    dp[u][2] = b[a[u]][2];
    for(ll s : g[u]){
        if(s==par) continue;
        dfs2(s,u);
        dp[u][1] = min(dp[u][1],dp[s][1]);
        dp[u][2] = max(dp[u][2],dp[s][2]);
        bio[u]|=bio[s];
    }
    bool da = 0;
    if(u!=par){
        if(intree(dp[u][1],u)&&intree(dp[u][2],u)) da = 1;
    }
    //cerr<<"u: "<<u<<" "<<in[u]<< " "<<out[u]<<" "<<dp[u][1]<< " "<<dp[u][2]<<endl;
    if(da){
        mp[{u,par}] = mp[{par,u}] = 1;
    }
}
bool vis[maxn];
void dfs3(ll u,ll par){
    vis[u] = 1;
    for(ll s : g[u]){
        if(s==par) continue;
        if(mp[{s,u}]) continue;
        upd(u,s);
        dfs3(s,u);
    }
}
vector<pll> e;
int main(){
	ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);
    cin >> n >> k;
    iota(dsu+1,dsu+n+1,1);
    for(ll i = 1;i<=n-1;i++){
        ll x,y; cin >> x >> y;
        g[x].pb(y);
        g[y].pb(x);
        e.pb({x,y});
    }
    for(ll i = 1;i<=n;i++) cin >> a[i];
    dfs(1,1);
    for(ll i = 1;i<=k;i++){
        b[i][1] = llinf;
        b[i][2] = 0;
    }
    for(ll i = 1;i<=n;i++){
        ll col = a[i];
        b[col][1] = min(b[col][1],in[i]);
        b[col][2] = max(b[col][2],in[i]);
    }
    dfs2(1,1);
    for(ll i = 1;i<=n;i++){
        if(vis[i]) continue;
        dfs3(i,i);
    }
    for(pll p : e){
        ll x = p.fi;
        ll y = p.sc;
        x = root(x);
        y = root(y);
        if(x==y) continue;
        rg[x].insert(y);
        rg[y].insert(x);
    }
    for(ll i = 1;i<=n;i++) if(sz(rg[i])==1) ans++;
    ans = (ans+1)/2;
    cout<<ans<<endl;
    return 0;
}
/*
5 4
1 2
2 3
3 4
3 5
1
2
1
3
4

5 4
1 2
2 3
3 4
4 5
1
2
3
4
1

5 5
1 2
2 3
3 4
4 5
1
2
3
4
5
*/

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