Submission #1264620

#	Time	Username	Problem	Language	Result	Execution time	Memory
1264620		tvgk	Capital City (JOI20_capital_city)	C++20	0 / 100	32 ms	12100 KiB

capital_city

#include<bits/stdc++.h>
using namespace std;
#define task "a"
#define ll long long
#define ii pair<ll, ll>
#define fi first
#define se second
const long mxN = 1e5 + 7;

int n, in[mxN], h[mxN], par[mxN][30], root[mxN], mn[mxN], k, num, c[mxN], ans, lst[mxN];
vector<int> w[mxN], ww[mxN];

void TiTo(int j)
{
    in[j] = ++num;

    h[j] = h[par[j][0]] + 1;
    for (int i = 1; i <= 20; i++)
        par[j][i] = par[par[j][i - 1]][i - 1];

    for (int i : w[j])
    {
        if (in[i])
            continue;

        par[i][0] = j;
        TiTo(i);
    }
}

bool cmp(int u, int v)
{
    return in[u] < in[v];
}

int LCA(int u, int v)
{
    if (h[u] < h[v])
        swap(u, v);

    for (int i = 20; i >= 0; i--)
    {
        if (h[par[u][i]] >= h[v])
            u = par[u][i];
    }

    if (u == v)
        return h[u];

    for (int i = 20; i >= 0; i--)
    {
        if (par[u][i] != par[v][i])
        {
            u = par[u][i];
            v = par[v][i];
        }
    }

    return h[u] - 1;
}

void DFS(int j)
{
    root[j] = h[mn[c[j]]];

    for (int i : w[j])
    {
        if (h[i] < h[j])
            continue;

        DFS(i);
        root[j] = min(root[j], root[i]);

        if (root[i] < h[i])
            ww[c[i]].push_back(c[j]);
    }
}

int cs[mxN], low[mxN], dsu[mxN], vis[mxN], block;
vector<int> vc;
void Tarzan(int j)
{
    if (j > n)
        return;

    cs[j] = low[j] = ++num;
    vis[j] = 1;
    vc.push_back(j);

    for (int i : ww[j])
    {
        if (!vis[i])
            Tarzan(i);

        if (vis[i] == 1)
            low[j] = min(low[i], low[j]);
    }

    if (low[j] != cs[j])
        return;

    bool tt = 0;
    int cntt = 0;
    block++;
    while (vis[j] == 1)
    {
        int i = vc.back();
        vc.pop_back();

        vis[i] = 2;
        dsu[i] = block;

        cntt++;
        for (int u : ww[i])
            tt |= (dsu[u] && dsu[u] != block);
    }

    if (!tt)
        ans = min(ans, cntt - 1);
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    //freopen(task".INP", "r", stdin);
    //freopen(task".OUT", "w", stdout);

    cin >> n >> k;
    for (int i = 1; i < n; i++)
    {
        int u, v;
        cin >> u >> v;
        w[u].push_back(v);
        w[v].push_back(u);
    }
    TiTo(1);

    for (int i = 1; i <= n; i++)
    {
        cin >> c[i];

        if (mn[c[i]])
            mn[c[i]] = LCA(mn[c[i]], i);
        else
            mn[c[i]] = i;
    }
    DFS(1);

    ans = n;
    for (int i = 1; i <= k; i++)
    {
        if (!vis[i])
            Tarzan(i);
    }
    cout << ans;
}

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