Submission #1691052


Source Code Expand

#include <cstdio>
#include <vector>
#include <algorithm>
using namespace std;

#define iter(i, n) for (int i = 1; i <= n; ++i)
#define NR 101000

const int mod = 1e9 + 7;

int n, a[NR], in[NR], in_x[NR], cnt[NR], f[NR], cc[NR], sz;
bool vis[NR], ring[NR];
vector<int> R[NR];

int main() {
	scanf("%d", &n);
	iter(i, n) {
		scanf("%d", &a[i]);
		++in[a[i]];
		in_x[a[i]] = i;
	}
	iter(i, n) if (in[i] > 2) { puts("0"); return 0; }
	int ans = 1;
	iter(i, n) if (!vis[i]) {
		int x = i; bool is_ring = true;
		for (; !vis[x]; x = a[x]) {
			vis[x] = true;
		}

		if (!ring[x]) {
			++sz;
			for (; !ring[x]; x = a[x]) {
				if (in[x] != 1) is_ring = false;
				ring[x] = true;
				R[sz].push_back(x);
			}
		}

		if (x != i) {
			bool is_chain = true;
			x = i;
			while (in[x] == 1) x = in_x[x];
			if (in[x] != 0) { puts("0"); return 0; }
			int len = 1;
			for (vis[x] = true, x = a[x]; !ring[x]; x = a[x]) {
				++len;
				vis[x] = true;
				if (in[x] != 1) { puts("0"); return 0; }
			}
			cc[x] = len;
		} else {
			if (is_ring) ++cnt[R[sz].size()];
		}
	}

	iter(i, sz) {
		reverse(R[i].begin(), R[i].end());
		int rem = 0;
		for (int x : R[i]) {
			if (cc[x] != 0) {
				if (rem > 1) { puts("0"); return 0; }
				else rem = cc[x];
			} else if (rem != 0) {
				--rem;
				if (rem == 0) ans = ans * 2 % mod;
			}	
		}

		if (rem != 0) {
			for (int x : R[i]) {
				if (cc[x] != 0) {
					if (rem > 1) { puts("0"); return 0; }
					else break;
				} else {
					--rem;
					if (rem == 0) {
						ans = ans * 2 % mod;
						break;
					}
				}
			}
		}
	}

	iter(k, n) {
		f[0] = 1;
		iter(i, cnt[k]) {
			f[i] = f[i - 1] * ((k % 2 && k != 1) ? 2 : 1) % mod;
			if (i > 1) f[i] = (f[i] + 1ll * (i - 1) * f[i - 2] % mod * k) % mod;
		}
		ans = 1ll * ans * f[cnt[k]] % mod;
	}
	printf("%d\n", ans);
	return 0;
}

Submission Info

Submission Time
Task E - Next or Nextnext
User Ketsui
Language C++14 (GCC 5.4.1)
Score 1400
Code Size 1905 Byte
Status AC
Exec Time 21 ms
Memory 8320 KB

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:16:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
                 ^
./Main.cpp:18:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &a[i]);
                     ^

Judge Result

Set Name Sample All
Score / Max Score 0 / 0 1400 / 1400
Status
AC × 5
AC × 59
Set Name Test Cases
Sample 0_00.txt, 0_01.txt, 0_02.txt, 0_03.txt, 0_04.txt
All 0_00.txt, 0_01.txt, 0_02.txt, 0_03.txt, 0_04.txt, 1_00.txt, 1_01.txt, 1_02.txt, 1_03.txt, 1_04.txt, 1_05.txt, 1_06.txt, 1_07.txt, 1_08.txt, 1_09.txt, 1_10.txt, 1_11.txt, 1_12.txt, 1_13.txt, 1_14.txt, 1_15.txt, 1_16.txt, 1_17.txt, 1_18.txt, 1_19.txt, 1_20.txt, 1_21.txt, 1_22.txt, 1_23.txt, 1_24.txt, 1_25.txt, 1_26.txt, 1_27.txt, 1_28.txt, 1_29.txt, 1_30.txt, 1_31.txt, 1_32.txt, 1_33.txt, 1_34.txt, 1_35.txt, 1_36.txt, 1_37.txt, 1_38.txt, 1_39.txt, 1_40.txt, 1_41.txt, 1_42.txt, 1_43.txt, 1_44.txt, 1_45.txt, 1_46.txt, 1_47.txt, 1_48.txt, 1_49.txt, 1_50.txt, 1_51.txt, 1_52.txt, 1_53.txt
Case Name Status Exec Time Memory
0_00.txt AC 3 ms 4352 KB
0_01.txt AC 3 ms 4352 KB
0_02.txt AC 3 ms 4352 KB
0_03.txt AC 3 ms 4352 KB
0_04.txt AC 3 ms 4352 KB
1_00.txt AC 3 ms 4352 KB
1_01.txt AC 21 ms 8320 KB
1_02.txt AC 21 ms 6784 KB
1_03.txt AC 21 ms 6272 KB
1_04.txt AC 18 ms 5756 KB
1_05.txt AC 18 ms 5756 KB
1_06.txt AC 18 ms 5756 KB
1_07.txt AC 18 ms 5760 KB
1_08.txt AC 18 ms 5756 KB
1_09.txt AC 13 ms 5120 KB
1_10.txt AC 18 ms 5756 KB
1_11.txt AC 16 ms 5756 KB
1_12.txt AC 18 ms 5504 KB
1_13.txt AC 18 ms 5504 KB
1_14.txt AC 16 ms 5504 KB
1_15.txt AC 18 ms 5756 KB
1_16.txt AC 17 ms 5756 KB
1_17.txt AC 17 ms 5756 KB
1_18.txt AC 18 ms 5756 KB
1_19.txt AC 18 ms 5756 KB
1_20.txt AC 18 ms 5756 KB
1_21.txt AC 18 ms 5756 KB
1_22.txt AC 18 ms 5756 KB
1_23.txt AC 18 ms 5756 KB
1_24.txt AC 16 ms 5756 KB
1_25.txt AC 18 ms 5756 KB
1_26.txt AC 17 ms 5504 KB
1_27.txt AC 18 ms 5504 KB
1_28.txt AC 16 ms 5504 KB
1_29.txt AC 16 ms 5504 KB
1_30.txt AC 18 ms 5632 KB
1_31.txt AC 18 ms 5632 KB
1_32.txt AC 18 ms 5632 KB
1_33.txt AC 18 ms 5696 KB
1_34.txt AC 18 ms 5504 KB
1_35.txt AC 18 ms 5504 KB
1_36.txt AC 16 ms 5504 KB
1_37.txt AC 16 ms 5504 KB
1_38.txt AC 18 ms 5376 KB
1_39.txt AC 18 ms 5376 KB
1_40.txt AC 16 ms 5376 KB
1_41.txt AC 15 ms 5376 KB
1_42.txt AC 19 ms 5888 KB
1_43.txt AC 20 ms 5888 KB
1_44.txt AC 19 ms 5888 KB
1_45.txt AC 20 ms 5888 KB
1_46.txt AC 20 ms 5760 KB
1_47.txt AC 19 ms 5632 KB
1_48.txt AC 18 ms 5760 KB
1_49.txt AC 18 ms 5632 KB
1_50.txt AC 20 ms 5888 KB
1_51.txt AC 19 ms 5888 KB
1_52.txt AC 19 ms 5888 KB
1_53.txt AC 20 ms 5888 KB