Submission #261348

#	Time	Username	Problem	Language	Result	Execution time	Memory
261348		doowey	Capital City (JOI20_capital_city)	C++14	100 / 100	1151 ms	42224 KiB

capital_city

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

#define fi first
#define se second
#define mp make_pair
#define fastIO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

const int N = (int)2e5 + 100;
vector<int> Z[N];
vector<int> T[N];
int id[N];
bool ban[N];
int par[N];
int subt[N];

bool now[N];

vector<int> mark;

void dfs(int u, int pr){
    subt[u] = 1;
    now[u]=true;
    mark.push_back(u);
    for(auto x : T[u]){
        if(ban[x] || x == pr) continue;
        dfs(x, u);
        subt[u] += subt[x];
    }
}

int up[N];

void dfs1(int u, int pr){
    up[u] = pr;
    for(auto x : T[u]){
        if(ban[x] || x == pr) continue;
        dfs1(x, u);
    }
}

int fin(int u){
    if(par[u]==u)
        return u;
    return par[u]=fin(par[u]);
}

int res;

void decomp(int node){
    mark.clear();
    dfs(node, -1);
    int pr = -1;
    bool is = true;
    int sz = subt[node];
    while(is){
        is = false;
        for(auto x : T[node]){
            if(x == pr || ban[x]) continue;
            if(subt[x] > sz/2){
                pr = node;
                node = x;
                is = true;
                break;
            }
        }
    }
    dfs1(node, node);
    set<int> has, need;
    need.insert(id[node]);
    int cur = 0;
    bool valid = true;
    int hh;
    while(!need.empty() && valid){
        auto it = need.begin();
        cur ++ ;
        for(auto x : Z[(*it)]){
            if(!now[x]){ // big optimization
                valid=false;
                break;
            }
        }

        if(!valid) break;
        set<int> piss;
        for(auto x : Z[(*it)]){

            hh = x;
            while(hh != node){
                hh=fin(hh);
                if(!need.count(id[hh]) && !has.count(id[hh]) && !piss.count(id[hh])){
                    piss.insert(id[hh]);
                }
                par[hh] = up[hh];
            }
        }
        has.insert(*it);
        need.erase(it);
        for(auto q : piss)
            need.insert(q);
    }
    if(valid){
        res = min(res, cur);
    }
    for(auto q : mark){
        now[q]=false;
        par[q]=q;
    }
    ban[node]=true;
    for(auto x : T[node]){
        if(!ban[x])
            decomp(x);
    }
}

int main(){
    fastIO;
    int n, k;
    cin >> n >> k;
    for(int i =1; i <= n; i ++ )
        par[i]=i;
    res = k;
    int u, v;
    for(int i = 1; i < n; i ++ ){
        cin >> u >> v;
        T[u].push_back(v);
        T[v].push_back(u);
    }
    for(int i = 1; i <= n; i ++ ){
        cin >> id[i];
        Z[id[i]].push_back(i);
    }
    decomp(1);
    cout << res - 1;
    return 0;
}

• Subtask 1: 1 / 1
• Subtask 2: 10 / 10
• Subtask 3: 30 / 30
• Subtask 4: 59 / 59