Submission #1235409

#	Time	Username	Problem	Language	Result	Execution time	Memory
1235409		poat	Capital City (JOI20_capital_city)	C++17	0 / 100	433 ms	44188 KiB

capital_city

// #pragma GCC optimize("Ofast")
// #pragma GCC target("popcnt")
 
#include <bits/stdc++.h>
using namespace std;
 
#define int long long
// #define double long double
#define mkp make_pair
 
#define txt freopen("shortcut.in", "r", stdin), freopen("shortcut.out", "w", stdout);
const int N = 2e5 + 100, K = 50, inf = 1e14, mod = 1e9 + 7;
const double eps = 1e-6;

vector<int> gr[N];
int Col[N];
vector<int> C[N];
bool blocked[N];

int CntCol[N];
bool vis[N];
bool usCol[N];


int cnt[N];
bool used[N];
int P[N];

void dfs(int x, int par)
{
    P[x] = par; 
    cnt[x] = 1;
    for(auto i : gr[x])
    {
        if(i == par || used[i])
            continue;
        
        dfs(i, x);
        cnt[x] += cnt[i];
    }
}


int find(int x, int par, int m)
{
    bool res = (cnt[x] >= ((m + 1) / 2));

    for(auto i : gr[x])
    {
        if(i == par || used[i])
            continue;
        
        res = min(res, (cnt[i] <= ((m + 1) / 2)));
        
        int k = find(i, x, m);
        if(k != -1)
            return k;
    }

    if(res)
        return x;
    return -1;
}


vector<int> vec;
void kol(int x, int par)
{
    vec.push_back(x);
    for(auto i : gr[x])
    {
        if(i == par || used[i])
            continue;
        kol(i, x);
    }
}

int solve(int x)
{       
    if(vec.size() == 1)
        return 1e9;
        // return (C[Col[x]].size() == 1 ? 0 : 1e9);
    
    int cent = find(x, 0, vec.size());

    dfs(cent, 0);
    used[cent] = 1;

    for(auto i : vec)
        CntCol[Col[i]]++;
    
    for(auto i : vec)
    {
        if(CntCol[Col[i]] != C[Col[i]].size())
            blocked[Col[i]] = 1;
    }

    bool fl = 0;

    int res = 0;

    vis[0] = 1;
    if(!blocked[Col[x]])
    {
        fl = 1;
        queue<int> Q;
        for(auto i : C[Col[x]])
            Q.push(i);
        usCol[Col[x]] = 1;

        while(!Q.empty())
        {   
            int y = Q.front();
            Q.pop();

            while(!vis[y])
            {
                vis[y] = 1;
                if(blocked[Col[y]])
                {
                    fl = 0;
                    break;
                }
                
                if(!usCol[Col[y]])
                {
                    usCol[Col[y]] = 1;
                    res++;
                    for(auto i : C[Col[y]])
                        Q.push(i);
                }
                y = P[y];
            }

            if(!fl)
                break;
            

        }
    }

    if(!fl)
        res = 1e9;
    for(auto i : vec)
        usCol[Col[i]] = vis[i] = CntCol[i] = 0;
    
    
    for(auto i : gr[cent])
    {
        if(used[i])
            continue;

        vec.clear();
        kol(i, cent);
        res = min(res, solve(i));
    }

    return res;
}   


void solve()
{
    int n, k;
    cin >> n >> k;

    for(int i = n - 1, a, b; i--;)
    {
        cin >> a >> b;
        gr[a].push_back(b);
        gr[b].push_back(a);
    }  

    for(int i = 1; i <= n; i++)
    {
        cin >> Col[i];
        C[Col[i]].push_back(i);

        vec.push_back(i);
    }

    dfs(1, 0);

    int ans = solve(1);
    assert(ans < n);
    cout << ans << '\n';


}

signed main()
{   
    // txt;
    // ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    int T = 1;
    for(; T--; solve());
}
/*
*/

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