結果

問題 No.778 クリスマスツリー
コンテスト
ユーザー ningenMe
提出日時 2020-01-22 01:57:02
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 122 ms / 2,000 ms
コード長 4,276 bytes
コンパイル時間 1,788 ms
コンパイル使用メモリ 174,664 KB
実行使用メモリ 25,076 KB
最終ジャッジ日時 2024-10-14 02:01:09
合計ジャッジ時間 3,459 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge2
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ファイルパターン 結果
sample AC * 3
other AC * 12
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>
using namespace std;
using ll = long long;
using ull = unsigned long long;

#define REP(i,n) for(long long i = 0; i < (n); i++)
#define FOR(i, m, n) for(long long i = (m);i < (n); ++i)
#define ALL(obj) (obj).begin(),(obj).end()
#define SPEED cin.tie(0);ios::sync_with_stdio(false);

template<class T> using V = vector<T>;
template<class T, class U> using P = pair<T, U>;
template<class T> using PQ = priority_queue<T>;
template<class T> using PQR = priority_queue<T,vector<T>,greater<T>>;

constexpr long long MOD = (long long)1e9 + 7;
constexpr long long MOD2 = 998244353;
constexpr long long HIGHINF = (long long)1e18;
constexpr long long LOWINF = (long long)1e15;
constexpr long double PI = 3.1415926535897932384626433;

template <class T> vector<T> multivector(size_t N,T init){return vector<T>(N,init);}
template <class... T> auto multivector(size_t N,T... t){return vector<decltype(multivector(t...))>(N,multivector(t...));}
template <class T> void corner(bool flg, T hoge) {if (flg) {cout << hoge << endl; exit(0);}}
template <class T, class U>ostream &operator<<(ostream &o, const map<T, U>&obj) {o << "{"; for (auto &x : obj) o << " {" << x.first << " : " << x.second << "}" << ","; o << " }"; return o;}
template <class T>ostream &operator<<(ostream &o, const set<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const multiset<T>&obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr) o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const vector<T>&obj) {o << "{"; for (int i = 0; i < (int)obj.size(); ++i)o << (i > 0 ? ", " : "") << obj[i]; o << "}"; return o;}
template <class T>ostream &operator<<(ostream &o, const deque<T>&obj) {o << "{"; for (int i = 0; i < (int)obj.size(); ++i)o << (i > 0 ? ", " : "") << obj[i]; o << "}"; return o;}
template <class T, class U>ostream &operator<<(ostream &o, const pair<T, U>&obj) {o << "{" << obj.first << ", " << obj.second << "}"; return o;}
template <template <class tmp>  class T, class U> ostream &operator<<(ostream &o, const T<U> &obj) {o << "{"; for (auto itr = obj.begin(); itr != obj.end(); ++itr)o << (itr != obj.begin() ? ", " : "") << *itr; o << "}"; return o;}
void print(void) {cout << endl;}
template <class Head> void print(Head&& head) {cout << head;print();}
template <class Head, class... Tail> void print(Head&& head, Tail&&... tail) {cout << head << " ";print(forward<Tail>(tail)...);}
template <class T> inline void chmax(T& a, const T b){a=max(a,b);}
template <class T> inline void chmin(T& a, const T b){a=min(a,b);}
void YN(bool flg) {cout << (flg ? "YES" : "NO") << endl;}
void Yn(bool flg) {cout << (flg ? "Yes" : "No") << endl;}
void yn(bool flg) {cout << (flg ? "yes" : "no") << endl;}


//Binary Indexed Tree
template<class Operator> class BinaryIndexedTree {
	Operator Op;                                         //Operator 演算子、型、単位元を持つ
	using typeNode = decltype(Op.unitNode);              //nodeの型
	int N;
	vector<typeNode> node;

public:
	BinaryIndexedTree(int N) : N(N), node(N + 1, Op.unitNode) {
		//do nothing
	}
 
	//[idx,idx+1)の値を更新
	void update(int idx, typeNode var) {
		for (++idx; idx <= N; idx += idx & -idx) node[idx] = Op.funcMerge(node[idx],var);
	}

	//[0,idx)の値を取得
	typeNode getvar(int idx) {
		typeNode ret = Op.unitNode;
		for (; idx >= 1; idx -= idx & -idx) ret = Op.funcMerge(ret,node[idx]);
		return ret;
	}
};

template<class typeNode> struct nodeAddRangeSum {
	typeNode unitNode = 0;
	typeNode funcNode(typeNode l,typeNode r){return l+r;}
	typeNode funcMerge(typeNode l,typeNode r){return l+r;}
};

//verify https://atcoder.jp/contests/chokudai_S001/tasks/chokudai_S001_j

vector<vector<int>> edge;
BinaryIndexedTree<nodeAddRangeSum<ll>> bit(200001);
ll ans = 0;
void dfs(int curr){
	bit.update(curr,1);
	ans += bit.getvar(curr);
	for(int next:edge[curr]) dfs(next);
	bit.update(curr,-1);
}

int main() {
	int N; cin >> N;
	edge.resize(N);
	for(int i = 1; i < N; ++i){
		int A; cin >> A;
		edge[A].push_back(i);
	}
	dfs(0);
	cout << ans << endl;





	return 0;
}
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