oj.uz

답안 #19257

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
19257 2016-02-23T06:11:19 Z kaTkaHr 트리 (kriii4_X) C++14
9 / 100
 0 ms 1216 KB 
#include <stdio.h>
#include<vector>
#include <algorithm>
#include <map>

using namespace std;

typedef long long ll;

const int MX = 105, MM = 1000000007;

ll pw(ll A, ll B){
    ll R = 1;
    while(B){
        if( B&1 ) R = R * A % MM;
        A = A * A % MM; B /= 2;
    }
    return R;
}

ll rv(ll A){ return pw(A, MM-2); }

struct frac{
    ll A, B;
		frac(ll A):A(A), B(1){}
    frac(ll a, ll b){
        A = (a%MM+MM) % MM;
        B = (b%MM+MM) % MM;
    }
    frac(){A = 0, B = 1;}
    frac operator+ (const frac &l)const{
        return frac((A * l.B + B * l.A) % MM, B * l.B % MM);
    }
    frac operator*(const frac &l)const{
        return frac(A*l.A % MM, B*l.B % MM);
    }
    frac operator/(const frac &l)const{
        return frac(A*l.B % MM, B*l.A % MM);
    }
    frac operator- (const frac &l)const{
        return frac((A*l.B - B*l.A%MM + MM) % MM, B*l.B % MM);
    }
    ll v(){ return A * rv(B) % MM; }
};

map<int, int> label;
struct UF{
	int p[MX], cnt[MX];
	UF(){ fill(cnt, cnt+MX, 1); }
	int find(int x){ return !p[x]? x : p[x] = find(p[x]); }
	int merge(int x, int y){
		x = find(x), y = find(y);
		if( x == y ) return false;
		p[x] = y;
		cnt[y] += cnt[x];
		return true;
	}
}uf;

int main()
{
	int N, M, cnt = 0;
	scanf("%d%d", &N, &M);
	for(int i = 1; i <= M; i++){
		int A, B;
		scanf("%d%d", &A, &B);
		if( label[A] == 0 ) label[A] = ++cnt;
		if( label[B] == 0 ) label[B] = ++cnt;
		A = label[A], B = label[B];
		if( !uf.merge(A, B) ) return !printf("0");
	}
	frac ans = 1, tot = 0;
	for(int i = 1; i <= cnt; i++){
		if( i == uf.find(i) ) ans = ans * uf.cnt[i];
	}
	ans = ans * pw(N, N-M-2);
	if(M+1 == N) return !printf("1");
	printf("%lld\n", ans.v());
}

Subtask #1
9.0 / 9.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 1216 KB Output is correct
2 Correct 0 ms 1216 KB Output is correct
3 Correct 0 ms 1216 KB Output is correct
4 Correct 0 ms 1216 KB Output is correct
5 Correct 0 ms 1216 KB Output is correct
6 Correct 0 ms 1216 KB Output is correct
7 Correct 0 ms 1216 KB Output is correct
8 Correct 0 ms 1216 KB Output is correct
9 Correct 0 ms 1216 KB Output is correct
10 Correct 0 ms 1216 KB Output is correct
11 Correct 0 ms 1216 KB Output is correct
12 Correct 0 ms 1216 KB Output is correct
13 Correct 0 ms 1216 KB Output is correct
14 Correct 0 ms 1216 KB Output is correct
15 Correct 0 ms 1216 KB Output is correct
16 Correct 0 ms 1216 KB Output is correct
17 Correct 0 ms 1216 KB Output is correct
18 Correct 0 ms 1216 KB Output is correct
19 Correct 0 ms 1216 KB Output is correct
20 Correct 0 ms 1216 KB Output is correct
21 Correct 0 ms 1216 KB Output is correct
22 Correct 0 ms 1216 KB Output is correct
23 Correct 0 ms 1216 KB Output is correct
24 Correct 0 ms 1216 KB Output is correct
25 Correct 0 ms 1216 KB Output is correct
26 Correct 0 ms 1216 KB Output is correct
27 Correct 0 ms 1216 KB Output is correct
28 Correct 0 ms 1216 KB Output is correct
29 Correct 0 ms 1216 KB Output is correct
30 Correct 0 ms 1216 KB Output is correct

Subtask #2
0.0 / 91.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 0 ms 1216 KB Output isn't correct
2 Halted 0 ms 0 KB -