Submission #1299380

#	Time	Username	Problem	Language	Result	Execution time	Memory
1299380		Zbyszek99	Mergers (JOI19_mergers)	C++20	100 / 100	597 ms	67924 KiB

mergers

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;

vi graph[500001];
int color[500001];
int precolor[500001];
int precolor2[500001];
int pre[500001];
int maxpre[500001];
int cur_pre;
bool block[500001];
bool odw[500001];
int P[500001];
vi ls;
int cnt = 0;

void dfs_pre(int v, int pop)
{
    P[v] = pop;
    ls.pb(v);
    pre[v] = cur_pre++;
    maxpre[v] = pre[v];
    forall(it,graph[v])
    {
        if(it != pop)
        {
            dfs_pre(it,v);
            maxpre[v] = maxpre[it];
        }
    }
}

pii dfs_block(int v, int pop)
{
    int min_ = precolor[color[v]];
    int max_ = precolor2[color[v]];
    forall(it,graph[v])
    {
        if(it != pop)
        {
            pii x = dfs_block(it,v);
            min_ = min(min_,x.ff);
            max_ = max(max_,x.ss);
        }
    }
    if(min_ == pre[v] && max_ == maxpre[v] && pop != v) block[v] = 1;
    return {min_,max_};
}

void dfs_ans(int v, int pop)
{
    if(block[v])
    {
        cnt++;
        if(v != pop) return;
    }
    odw[v] = 1;
    forall(it,graph[v])
    {
        if(it != P[v]) dfs_ans(it,v);
    }
}

int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    //random_start();
    int n,k;
    cin >> n >> k;
    rep2(i,1,k) precolor[i] = 1e9;
    rep(i,n-1)
    {
        int a,b;
        cin >> a >> b;
        graph[a].pb(b);
        graph[b].pb(a);
    }
    dfs_pre(1,1);
    rep2(i,1,n) cin >> color[i];
    rep2(i,1,n) precolor[color[i]] = min(precolor[color[i]],pre[i]);
    rep2(i,1,n) precolor2[color[i]] = max(precolor2[color[i]],maxpre[i]);
    dfs_block(1,1);
    int ans = 0;
    forall(it,ls)
    {
        if(odw[it]) continue;
        cnt = 0;
        dfs_ans(it,it);
        if(cnt <= 1) ans++;
    }
    if(ans == 1) cout << "0\n";
    else cout << (ans+1)/2 << "\n";
}

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