結果

問題 No.2638 Initial fare
ユーザー airthsairths
提出日時 2024-02-19 21:34:21
言語 C++17(gcc12)
(gcc 12.3.0 + boost 1.87.0)
結果
AC  
実行時間 369 ms / 2,000 ms
コード長 3,382 bytes
コンパイル時間 1,424 ms
コンパイル使用メモリ 136,672 KB
実行使用メモリ 77,060 KB
最終ジャッジ日時 2024-09-29 01:30:03
合計ジャッジ時間 6,410 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge1
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 * 25
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 # 

/*
 * 
 * 	^v^
 * 
 */
#include <iostream>
#include <numeric>
#include <set>
#include <iomanip>
#include <chrono>
#include <queue>
#include <string>
#include <vector>
#include <functional>
#include <map>
#include <bitset>
#include <algorithm>
#include <array>
#include <random>

using namespace std;

using ll = long long int;
using ld = long double;

#define iamtefu ios_base::sync_with_stdio(false); cin.tie(0);
#define fl(i,a,n) for (ll i{a}; i<n; i++)
#define fr(x,s) for(auto x:s)
#define rfl(i,a,n) for (ll i{n-1}; i>=a; i--)
#define ty int _; for(cin>>_; _--;)
#define print(a) for(auto ele:a){cout<<ele<<" ";}cout<<'\n';
#define all(x) x.begin(), x.end()

template <typename L, typename R>
inline bool chmax(L &a, R b){if (a<b){a=b;return 1;}return 0;}
template <typename L, typename R>
inline bool chmin(L &a, R b){if (a>b){a=b;return 1;}return 0;}

template <typename L, typename R>
ostream& operator<<(ostream &fout, const pair<L, R> &p){
	fout<<"{"<<p.first<<","<<p.second<<"}";
	return fout;
}

template <typename L, typename R, typename U>
ostream& operator<<(ostream &fout, const tuple<L, R, U> &p){
	auto &[l, r, u] = p;
	fout<<"{"<<l<<","<<r<<","<<u<<"}";
	return fout;
}

template <typename T>
ostream& operator<<(ostream &fout, const vector <T> &v){
	for (auto &x:v){
		fout<<x<<" ";
	}
	fout<<"\n";
	return fout;
}

template <typename T>
ostream& operator<<(ostream &fout, const set <T> &st){
	for (auto &x:st){
		fout<<x<<" ";
	}
	fout<<"\n";
	return fout;
}

template <typename T>
ostream& operator<<(ostream &fout, const multiset <T> &st){
	for (auto &x:st){
		fout<<x<<" ";
	}
	fout<<"\n";
	return fout;
}

template <typename K, typename V>
ostream& operator<<(ostream &fout, const map<K, V> &mp){
	fout<<"[";
	for (auto &[x,y]:mp){
		fout<<x<<":"<<y<<" ";
	}
	fout<<"]\n";
	return fout;
}

ll gcd(ll a, ll b){
	if (b==0){
		return a;
	}
	return gcd(b, a%b);
}

mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());

ll pw(ll a, ll b, ll m){
	ll res=1;
	a%=m;
	while (b){
		if (b&1){
			res=(res*a)%m;
		}
		a=(a*a)%m;
		b/=2;
	}
	return res;
}

void scn(){
	// not necessarily distinct
	// right down
	
	ll n; cin>>n;
	vector <vector <ll>> ed(n+1);
	fl(i,0,n-1){
		ll u, v; cin>>u>>v;
		ed[u].push_back(v);
		ed[v].push_back(u);
	}
	vector <ll> vis(n+1);
	vector <vector <ll>> dp(n+1, vector <ll>(4, 0));
	auto dfs=[&](const auto &self, ll i)->void{
		vis[i]++;
		for (auto x:ed[i]){
			if (!vis[x]){
				self(self, x);
				fl(k,0,3){
					dp[i][k+1]+=dp[x][k];
				}
			}
		}
		dp[i][0]=1;
	};
	dfs(dfs, 1);
	ll ans = 0;
	auto df=[&](const auto &self, ll i)->void{
		vis[i]++;
		fl(j,1,4){
			ans+=dp[i][j];
		}
		for (auto x:ed[i]){
			if (!vis[x]){
				auto pr = dp[x], pr1 = dp[i];
				fl(k,0,3){
					dp[i][k+1]-=dp[x][k];
				}
				fl(k,0,3){
					dp[x][k+1]+=dp[i][k];
				}
				self(self, x);
				swap(dp[i], pr1);
				swap(dp[x], pr);
			}
		}
	};
	fill(vis.begin(), vis.end(), 0);
	df(df, 1);
	cout<<ans/2<<'\n';
}

int main(){
	iamtefu;
#if defined(airths)
	auto t1=chrono::high_resolution_clock::now();
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
	// ty
	{
		scn();
	}
#if defined(airths)
	auto t2=chrono::high_resolution_clock::now();
	ld ti=chrono::duration_cast<chrono::nanoseconds>(t2-t1).count();
	ti*=1e-6;
	cerr<<"Time: "<<setprecision(12)<<ti;
	cerr<<"ms\n";
#endif
	return 0;
}
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