結果

問題 No.778 クリスマスツリー
ユーザー nanophoto12
提出日時 2021-05-23 15:07:30
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 174 ms / 2,000 ms
コード長 2,912 bytes
コンパイル時間 4,434 ms
コンパイル使用メモリ 256,272 KB
最終ジャッジ日時 2025-01-21 17:44:31
ジャッジサーバーID
(参考情報)
judge2 / judge4
このコードへのチャレンジ
(要ログイン)
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 #
プレゼンテーションモードにする

#include <bits/stdc++.h>
#define M_PI 3.14159265358979323846 // pi
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;
#define rep(a,n) for(ll a = 0;a < n;a++)
#define repi(a,b,n) for(ll a = b;a < n;a++)
template<typename T>
void chmax(T& reference, T value) {
reference = max(reference, value);
}
template<typename T>
void chmaxmap(map<T, T>& m, T key, T value) {
if (m.count(key)) {
chmax(m[key], value);
}
else {
m[key] = value;
}
}
template<typename T>
void chmin(T& reference, T value) {
reference = min(reference, value);
}
#include <atcoder/all>
using namespace atcoder;
typedef modint1000000007 mint;
struct Point {
ll x, y;
bool operator <(const Point& p) const {
return x < p.x || (x == p.x && y < p.y);
}
};
struct ConvexHullRunner {
typedef ll coord_t;
typedef ll coord2_t;
coord2_t cross(const Point& O, const Point& A, const Point& B)
{
return (A.x - O.x) * (B.y - O.y) - (A.y - O.y) * (B.x - O.x);
}
vector<Point> convex_hull(vector<Point> P)
{
size_t n = P.size(), k = 0;
if (n <= 3) return P;
vector<Point> H(2 * n);
sort(P.begin(), P.end());
for (size_t i = 0; i < n; ++i) {
while (k >= 2 && cross(H[k - 2], H[k - 1], P[i]) <= 0) k--;
H[k++] = P[i];
}
for (size_t i = n - 1, t = k + 1; i > 0; --i) {
while (k >= t && cross(H[k - 2], H[k - 1], P[i - 1]) <= 0) k--;
H[k++] = P[i - 1];
}
H.resize(k - 1);
return H;
}
};
ll gcd(ll a, ll b) { while (b) a %= b, swap(a, b); return abs(a); }
static ll raw_cmb(ll n, ll k) {
ll c = 1;
for (int i = 1; i <= k; i++) {
c *= (n + 1 - i);
c /= i;
}
return c;
}
struct BIT {
typedef ll input_t;
vector<input_t> bit_;
const long long n_;
BIT(long long n) :n_(n) {
bit_.resize(n + 1LL, 0);
}
input_t sum(int i) {
input_t s = 0;
while (i > 0) {
s += bit_[i];
i -= i & (-i);
}
return s;
}
void add(int i, input_t x) {
while (i <= n_) {
bit_[i] += x;
i += (i & (-i));
}
}
};
int main() {
int n;
cin >> n;
vector<vector<int>> g(n + 1);
for (int i = 1; i < n;i++) {
ll p;
cin >> p;
g[p + 1].push_back(i + 1);
}
BIT bit(n);
ll sum = 0;
function<void(ll, ll)> dfs = [&](ll current, ll parent) {
sum += bit.sum(current);
bit.add(current, 1);
for (auto x : g[current]) {
if (x == parent) continue;
dfs(x, current);
}
bit.add(current, -1);
};
dfs(1, -1);
cout << sum << endl;
return 0;
}
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
0