結果

問題 No.3217 Shiki no Shiki
ユーザー ont
提出日時 2025-08-01 22:29:13
言語 C++23
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 47 ms / 2,000 ms
コード長 2,851 bytes
コンパイル時間 5,007 ms
コンパイル使用メモリ 335,660 KB
実行使用メモリ 11,008 KB
最終ジャッジ日時 2025-08-01 22:29:21
合計ジャッジ時間 6,354 ms
ジャッジサーバーID
(参考情報)
judge4 / judge3
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 23
権限があれば一括ダウンロードができます

ソースコード

diff #

#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
template<typename T> using pq = priority_queue<T>;
template<typename T> using pq_g = priority_queue<T, vector<T>, greater<T>>;
using mint = modint998244353;
// using mint = modint1000000007;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define NP next_permutation
#define debug(x) cerr << #x << " = " << (x) << endl
const int INF = 2e9;
const ll LINF = 2e18;
const ll mod = 998244353;
// const ll mod = 1000000007;
void Yes(bool a) {cout << (a ? "Yes" : "No") << endl;}
void YES(bool a) {cout << (a ? "YES" : "NO") << endl;}
void Possible(bool a) {cout << (a ? "Possible" : "Impossible") << endl;}
void POSSIBLE(bool a) {cout << (a ? "POSSIBLE" : "IMPOSSIBLE") << endl;}
template<typename T> void vcin(vector<T> &a) {rep(i, int(a.size())) cin >> a[i];}
template<typename T, typename K> void vcin(vector<T> &a, vector<K> &b) {rep(i, int(a.size())) cin >> a[i] >> b[i];}
template<typename T> void vcout(vector<T> &a) {rep(i, int(a.size())) {cout << a[i] << " ";} cout << endl;}
template<typename T> void vcin(vector<vector<T>> &a) {rep(i, int(a.size())) rep(j, (int)a[i].size()) cin >> a[i][j];}
template<typename T> void vcout(vector<vector<T>> &a) {rep(i, int(a.size())) {rep(j, int(a[i].size())) {cout << a[i][j] << " ";} cout << endl;} cout << endl;}
template<typename T> auto vmin(vector<T> &a) {return *min_element(all(a));}
template<typename T> auto vmax(vector<T> &a) {return *max_element(all(a));}
template<typename T> auto vsum(vector<T> a) {return accumulate(all(a), T(0));}
template<typename T> bool chmin(T &a, T b){if(a > b){a = b; return true;} return false;}
template<typename T> bool chmax(T &a, T b){if(a < b){a = b; return true;} return false;}

void cincout() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(15);
}
 
int main() {
    cincout();

    int N;
    cin >> N;
    vector<ll> P(N), id(N, -1);
    vector<vector<int>> G(N);
    for (int i = 0; i < N; i++) {
        cin >> P[i];
        P[i]--;
        if (P[i] != -1) id[P[i]] = i;
        if (P[i] != -1) G[i].push_back(P[i]);
    }

    vector<int> ans(N, 0);
    for (int i = 0; i < N; i++) {
        if (id[i] != -1) continue;

        queue<pair<int, int>> q;
        q.push({i, 0});
        vector<bool> seen(N);
        while (!q.empty()) {
            auto [v, d] = q.front();
            q.pop();

            seen[v] = true;
            if (d == 2) ans[v] = 1;

            for (int next_v : G[v]) {
                if (d == 2) continue;
                if (!seen[next_v]) q.push({next_v, d + 1});
            }
        }
    }

    cout << vsum(ans) << endl;
}
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