Submission #1281016

#	Time	Username	Problem	Language	Result	Execution time	Memory
1281016		vuquangsang	Capital City (JOI20_capital_city)	C++20	11 / 100	3096 ms	49516 KiB

capital_city

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

#define     el "\n"
#define     FOR(i,a,b) for(int i = (a), _b = (b); i <= _b; i++)
#define     FORD(i,a,b) for(int i = (a), _b = (b); i >= _b; i--)
#define     pb push_back
#define     fi first
#define     se second
#define     all(x) x.begin(),x.end()
#define     lg(x) __lg(x)
#define     alla(a,n) a+1,a+n+1
#define     ll long long
#define     debug(x) cout << (x) << " ";
#define     c_bit(msk) __builtin_popcount(msk)

template <class T> bool maxi(T &x, T y) { if(x < y) { x = y ; return true ;} return false;}
template <class T> bool mini(T &x, T y) { if(x > y) { x = y ; return true ;} return false;}

const int N = 2e5 + 2;

int n, a[N], k;
vector<int> adj[N];
pair<int, int> E[N];
vector<int> pos[N];

void inp()
{
    cin >> n >> k;
    FOR(i, 1, n - 1) {
        int x, y; cin >> x >> y;
        E[i] = {x, y};
        adj[x].pb(y);
        adj[y].pb(x);
    }
    FOR(i, 1, n) {
        cin >> a[i];
        pos[a[i]].push_back(i);
    }
}

/* Try your best
    No regrets */

namespace subtask_1
{
    struct DSU
    {
        int lab[N];
        int root(int x)
        {
            return lab[x] < 0 ? x : lab[x] = root(lab[x]);
        }
        bool joint(int x, int y)
        {
            x = root(x); y = root(y);
            if(x == y) return 0;
            if(lab[x] > lab[y]) swap(x, y);
            lab[x] += lab[y];
            lab[y] = x;
            return 1;
        }
    } dsu;


    bool ok[N];
    int temp[N];

    int cnt[N];
    void slv()
    {
        int ans = k - 1;
        for(int msk = 0; msk < (1 << k); msk++) {
            FOR(i, 1, n) temp[i] = a[i];

            for(int i = 1; i <= k; i++) ok[i] = 0;

            int uwu = 0;
            for(int color = 0; color < k; color++) if(msk >> color & 1) {
                if(!uwu) uwu = color + 1;
                ok[color + 1] = 1;
            }

            FOR(i, 1, n) if(ok[temp[i]]) temp[i] = uwu;

            for(int i = 1; i <= n; i++) dsu.lab[i] = -1;
            FOR(i, 1, n - 1) {
                int x = E[i].first, y = E[i].second;
                if(temp[x] == temp[y] && temp[x] == uwu) {
                    dsu.joint(x, y);
                }
            }

            for(int i = 1; i <= k; i++) cnt[i] = 0;
            for(int i = 1; i <= n; i++) cnt[temp[i]]++;

//            for(int i = 1; i <= n; i++) cout << temp[i] << " "; cout << el;

            bool oke = 0;
            for(int i = 1; i <= n; i++) {
                int p = dsu.root(i);
                int number = dsu.lab[p];
                if(-number == cnt[temp[i]]) {
                    oke = 1;
                    break;
                }

            }
            if(oke) {
                if(!msk) ans = 0;
                else mini(ans, c_bit(msk) - 1);
            }
        }
        cout << ans;
    }
}

namespace subtask_2
{

    bool have[N];
    int h[N], up[N][21];
    int tin[N], time = 0;

    void dfs(int u, int p)
    {
        tin[u] = ++time;

        up[u][0] = p;
        FOR(j, 1, lg(n)) up[u][j] = up[up[u][j - 1]][j - 1];

        for(int v : adj[u]) if(v != p) {
            h[v] = h[u] + 1;
            dfs(v, u);
        }
    }
    int LCA(int u, int v)
    {
        if(h[u] < h[v]) swap(u, v);
        FORD(j, lg(n), 0) if(h[up[u][j]] >= h[v]) u = up[u][j];
        if(u == v) return u;
        FORD(j, lg(n), 0) if(up[u][j] != up[v][j]) {
            u = up[u][j];
            v = up[v][j];
        }
        return up[u][0];
    }

    vector<int> cur_city;

    void connect(int x, int y)
    {
        int p = LCA(x, y);
        while(x != p) {
            if(!have[a[x]]) cur_city.push_back(a[x]);
            have[a[x]] = 1;
            x = up[x][0];
        }
        while(y != p) {
            if(!have[a[y]]) cur_city.push_back(a[y]);
            have[a[y]] = 1;
            y = up[y][0];
        }
        if(!have[a[p]]) cur_city.push_back(a[p]);
        have[a[p]] = 1;
    }
    int getAns(int C)
    {
        cur_city.clear();
        cur_city.push_back(C);

        have[C] = 1;

        for(int id = 0; id < cur_city.size(); id++) {
            int x = cur_city[id];
            for(int i = 1; i < pos[x].size(); i++) {
                connect(pos[x][i], pos[x][i - 1]);
            }
        }
        for(int x : cur_city) have[x] = 0;
        return cur_city.size() - 1;
    }
    void slv()
    {
        dfs(1, 1);

        for(int i = 1; i <= k; i++) {
            sort(all(pos[i]), [&](int x, int y){
                 return tin[x] < tin[y];
            });
        }


        int ans = k - 1;
        FOR(i, 1, k) if(!have[i]) {
            mini(ans, getAns(i));
        }
        cout << ans;
    }
}

/* Code slowly, think carefully */

main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

    #define __Azul__ "capital_city"
    if(fopen(__Azul__".inp", "r")) {
        freopen(__Azul__".inp", "r", stdin);
        freopen(__Azul__".out", "w", stdout);
    }

    bool qs = 0;

    int T = 1;
    if(qs) cin >> T;
    while(T--) {
        inp();
        subtask_2::slv();
    }

    cerr << "\nTime" << 0.001 * clock() << "s "; return 0;


}

Compilation message (stderr)

capital_city.cpp:204:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  204 | main()
      | ^~~~
capital_city.cpp: In function 'int main()':
capital_city.cpp:210:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  210 |         freopen(__Azul__".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
capital_city.cpp:211:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  211 |         freopen(__Azul__".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 1 / 1
• Subtask 2: 10 / 10
• Subtask 3: 0 / 30
• Subtask 4: 0 / 59