paleta

#include <iostream>
#include <vector>
using namespace std;
int n, k, vi[1000000];
bool z[1000000];
vector<int> v[1000000];
long sum = 1;
void h(int i, int options) {
	if (z[i]) return;
	z[i] = 1;
	sum *= (long) options;
	sum %= 1000000007;
	int noptions = 0;
	for (int j : v[i]) {
		noptions += !z[j];
	}
	for (int j : v[i]) {
		h(j, k-noptions);
	}
}
int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> n >> k;
	vector<int> top;
	for (int i = 1; i <= n; ++i) {
		int c;
		cin >> c;
		vi[i-1] = c-1;
		if (c == i) {
			top.push_back(i);
		} else {
			v[c-1].push_back(i-1);
		}
	}
	for (int i : top) {
		h(i, k);
	}
	for (int i = 0; i < n; ++i) {
		h(i, k);
	}
	cout << max(sum, (long)0);
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: ACCEPTED

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: WRONG ANSWER

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: WRONG ANSWER

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: WRONG ANSWER

Test 20

Verdict: WRONG ANSWER

Test 21

Verdict: WRONG ANSWER

Test 22

Verdict: WRONG ANSWER

Test 23

Verdict: ACCEPTED