제출 #1264557

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1264557		tvgk	수도 (JOI20_capital_city)	C++20	0 / 100	31 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][20], 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])
            return;

        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];
bool vis[mxN];
vector<int> vc;
void Tarzan(int j)
{
    cout << j << '\n';

    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;
//    k++;
//    while (vis[j] == 1)
//    {
//        int i = vc.back();
//        vc.pop_back();
//
//        cout << i << " ";
//
//        vis[i] = 2;
//        dsu[i] = k;
//
//        cntt++;
//        for (int u : ww[i])
//            tt |= (dsu[u] && dsu[u] != k);
//
//        if (i == j)
//            break;
//    }
//
//    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);

    for (int i = 1; i <= k; i++)
    {
        cout << i << " : ";
        for (int j : ww[i])
            cout << j << " ";
        cout << '\n';
    }

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

컴파일 시 표준 에러 (stderr) 메시지

capital_city.cpp: In function 'void TiTo(int)':
capital_city.cpp:19:19: warning: iteration 19 invokes undefined behavior [-Waggressive-loop-optimizations]
   19 |         par[j][i] = par[par[j][i - 1]][i - 1];
      |         ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
capital_city.cpp:18:23: note: within this loop
   18 |     for (int i = 1; i <= 20; i++)
      |                     ~~^~~~~

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