結果

問題 No.778 クリスマスツリー
ユーザー fumiphysfumiphys
提出日時 2019-05-26 14:33:34
言語 C++14
(gcc 12.3.0 + boost 1.83.0)
結果
AC  
実行時間 75 ms / 2,000 ms
コード長 4,600 bytes
コンパイル時間 1,705 ms
コンパイル使用メモリ 175,476 KB
実行使用メモリ 23,168 KB
最終ジャッジ日時 2024-10-14 01:59:19
合計ジャッジ時間 2,969 ms
ジャッジサーバーID
（参考情報） 		judge3 / judge5
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 2 ms
5,248 KB
testcase_01 AC 2 ms
5,248 KB
testcase_02 AC 2 ms
5,248 KB
testcase_03 AC 1 ms
5,248 KB
testcase_04 AC 2 ms
5,248 KB
testcase_05 AC 2 ms
5,248 KB
testcase_06 AC 51 ms
23,144 KB
testcase_07 AC 26 ms
12,004 KB
testcase_08 AC 75 ms
17,008 KB
testcase_09 AC 71 ms
14,208 KB
testcase_10 AC 68 ms
14,336 KB
testcase_11 AC 70 ms
14,208 KB
testcase_12 AC 64 ms
14,208 KB
testcase_13 AC 41 ms
14,080 KB
testcase_14 AC 50 ms
23,168 KB
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 # 

// includes
#include <bits/stdc++.h>

// macros
#define ll long long int
#define pb emplace_back
#define mk make_pair
#define pq priority_queue
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define rep(i, n) FOR(i, 0, n)
#define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--)
#define irep(itr, st) for(auto itr = (st).begin(); itr != (st).end(); ++itr)
#define irrep(itr, st) for(auto itr = (st).rbegin(); itr != (st).rend(); ++itr)
#define vrep(v, i) for(int i = 0; i < (v).size(); i++)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end())
#define FI first
#define SE second
#define dump(a, n) for(int i = 0; i < n; i++)cout << a[i] << "\n "[i + 1 != n];
#define dump2(a, n, m) for(int i = 0; i < n; i++)for(int j = 0; j < m; j++)cout << a[i][j] << "\n "[j + 1 != m];
#define bit(n) (1LL<<(n))
#define INT(n) int n; cin >> n;
#define LL(n) ll n; cin >> n;
#define DOUBLE(n) double n; cin >> n;
using namespace std;

//  types
typedef pair<int, int> P;
typedef pair<ll, int> Pl;
typedef pair<ll, ll> Pll;
typedef pair<double, double> Pd;
typedef complex<double> cd;
 
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;
const int mod = 1e9 + 7;
const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, -1, 0, 1};

// solve
template <class T>bool chmax(T &a, const T &b){if(a < b){a = b; return 1;} return 0;}
template <class T>bool chmin(T &a, const T &b){if(a > b){a = b; return 1;} return 0;}
template <typename T> istream &operator>>(istream &is, vector<T> &vec){for(auto &v: vec)is >> v; return is;}
template <typename T> ostream &operator<<(ostream &os, const vector<T>& vec){for(int i = 0; i < vec.size(); i++){ os << vec[i]; if(i + 1 != vec.size())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){os << p.first << " " << p.second; return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const unordered_map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}

struct Tree{
  int n = 0;
  // child: [id[i] + 1, f[i]]
  vector<vector<int>> edges;
  vector<int> e, id, f;
  int at = 0;
  Tree(){}
  Tree(int n): n(n){
    edges.resize(n);
    e.resize(n);
    id.resize(n);
    f.resize(n);
  }
  void adde(int from, int to){
    edges[from].emplace_back(to);
  }
  void dfs(int i){
    e[at] = i;
    id[i] = at;
    at++;
    for(auto c: edges[i]){
      dfs(c);
    }
    f[i] = at;
  }
  void build(int r = 0){
    e.assign(n, -1);
    id.assign(n, -1);
    f.assign(n, -1);
    at = 0;
    dfs(r);
  }
};

template<typename T>
struct BIT_{
  int n;
  vector<T> bit;
  BIT_(int n_){
    n = n_;
    bit = vector<T>(n+1, 0);
  }
  void add(int a, T w){
    for(int x = a; x < n; x |= (x + 1)){
      bit[x] += w;
    }
  }
  T sum(int a){
    T res = 0;
    for(int x = a; x >= 0; x = (x & (x + 1)) - 1){
      res += bit[x];
    }
    return res;
  }
};

typedef struct BIT_<int> BITI;
typedef struct BIT_<long long> BITL;

int main(int argc, char const* argv[])
{
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  INT(n);
  Tree t(n);
  rep(i, n - 1){
    int a;
    cin >> a;
    t.adde(a, i + 1);
  }
  t.build();
  BITI bt(n);
  ll res = 0;
  for(int i = n - 1; i >= 0; i--){
    bt.add(t.id[i], 1);
    res += bt.sum(t.f[i] - 1) - bt.sum(t.id[i]);
  }
  cout << res << endl;
  return 0;
}
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