Submission #20019

#	Time	Username	Problem	Language	Result	Execution time	Memory
20019		emppu	트리 (kriii4_X)	C++14	100 / 100	169 ms	10812 KiB

X

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cstring>
#include <cassert>

#include <algorithm>
#include <vector>
#include <string>
#include <set>
#include <map>
#include <queue>
#include <deque>
#include <list>
#include <bitset>
#include <tuple>

using namespace std;

#define f0(_X,_Y) for(int (_X)=0;(_X)<(_Y);++(_X))
#define f1(_X,_Y) for(int (_X)=1;(_X)<=(_Y);++(_X))
#define ff(_X,_Y,_Z) for(int (_X)=(_Y);(_X)<=(_Z);++(_X))
#define fF(_X,_Y,_Z) for(int (_X)=(_Y);(_X)<(_Z);++(_X))
#define rf0(_X,_Y) for(int _X=(_Y)-1;(_X)>=0;--(_X))
#define rf1(_X,_Y) for(int _X=(_Y);(_X)>0;--(_X))
#define rff(_X,_Y,_Z) for(int _X=(_Y);(_X)>=(_Z);--(_X))
#define rfF(_X,_Y,_Z) for(int _X=(_Y);(_X)>(_Z);--(_X))
#define PRT(_X) std::cout<< #_X ": "<<_X<<std::endl;

#define scan1(_X) scanf("%d",&_X);
#define scan2(_X,_Y) scanf("%d%d",&_X,&_Y);
#define scan3(_X,_Y,_Z) scanf("%d%d%d",&_X,&_Y,&_Z);
#define define1(_1) int _1; scan1(_1)
#define define2(_1,_2) int _1,_2; scan2(_1,_2)
#define define3(_1,_2,_3) int _1,_2,_3; scan3(_1,_2,_3)
#define EXPAND(_1) _1
#define SELECT(_1,_2,_3,_4,NAME,...) NAME
#define scan(...) EXPAND(SELECT(__VA_ARGS__, scan4, scan3, scan2, scan1)(__VA_ARGS__))
#define define(...) EXPAND(SELECT(__VA_ARGS__, define4, define3, define2, define1)(__VA_ARGS__))
#define print(_X) printf("%d\n",_X)
#define PAIR_STRUCT(_T,_X,_Y,...) struct _T{int _X,_Y,##__VA_ARGS__; bool friend operator < (const _T &p, const _T &q){if(p._X!=q._X) return p._X<q._X; return p._Y<q._Y;}}

typedef long long ll;

const int MOD = 1000000007;
ll mul(ll a, ll b){return a*b%MOD;}
ll add(ll a, ll b){return (a+b)%MOD;}

ll inv(ll a, ll b=MOD)
{
	ll s = 0;  ll  old_s = 1;
	ll r = b;  ll  old_r = a;
	while (r!=0)
	{
		ll quotient = old_r / r;
		tie(old_r, r) = make_tuple(r, old_r - quotient * r);
		tie(old_s, s) = make_tuple(s, old_s - quotient * s);
	}
	ll inv = old_s%MOD;
	if(inv<0) inv += MOD;
	return inv;
}

const int N = 200002;
map<int,int> no;
int r[N],sz[N];

int root(int node)
{
	if(r[node]) return r[node]=root(r[node]);
	return node;
}

ll powmod(ll a, ll b)
{
	a %= MOD;
	b %= MOD-1;
	ll p = 1;
	ll sq = a;
	for(int i=1;i<=b;i*=2)
	{
		if(b&i)
		{
			p = mul(p,sq);
		}
		sq = mul(sq,sq);
	}
	return p;
}


int main()
{
	define(n,m);
	int cnt=0;
	bool cycle = false;
	f1(i,m)
	{
		define(s,e);
		if(no.find(s)==no.end()) no[s]=++cnt, s=cnt, sz[cnt]=1; else s=no[s];
		if(no.find(e)==no.end()) no[e]=++cnt, e=cnt, sz[cnt]=1; else e=no[e];
		int r1 = root(s);
		int r2 = root(e);
		if(r1!=r2)
		{
			r[r2]=r1;
			sz[r1]+=sz[r2];
		}
		else
		{
			cycle=true;
			break;
		}
	}
	if(cycle)
	{
		print(0);
		return 0;
	}
	if(m==n-1)
	{
		print(1);
		return 0;
	}

	ll ans=1;
	f1(i,cnt) if(r[i]==0) ans=mul(ans,sz[i]);


	ans = mul(ans,powmod(n,n-m-2));
	printf("%lld\n",ans);
	return 0;
}

• Subtask 1: 9 / 9
• Subtask 2: 91 / 91