oj.uz

Submission #763666

# Submission time Handle Problem Language Result Execution time Memory
763666 2023-06-22T15:15:05 Z parsadox2 Ruins 3 (JOI20_ruins3) C++14
100 / 100
 482 ms 3164 KB 
#include <bits/stdc++.h>
#define pb 		push_back
#define F		first
#define S 		second
#define debug(x)    cout << #x << "= " << x << ", "
#define ll 		long long
#define fast 		ios::sync_with_stdio(false), cin.tie(0),  cout.tie(0)
#define SZ(x)         (int) x.size()
#define wall 		cout << endl;
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int maxn = 605 , maxl = 1205 , mod = 1e9 + 7;
int n , ar[maxl] , fac[maxl] , dp[maxl][maxn] , f[maxn] , m2[maxn] , frev[maxl];

inline int mpo(int a , int b)
{
	int res = 1;
	while(b != 0)
	{
		if(b & 1)  res = 1LL * res * a % mod;
		b >>= 1;
		a = 1LL * a * a % mod;
	}
	return res;
}

inline int C(int a , int b)
{
	if(b > a || b < 0 || a < 0)  return 0;
	int res = 1LL * fac[a] * frev[b] % mod;
	res = 1LL * res * frev[a - b] % mod;
	return res;
}

int32_t main()
{
	fast;
	cin >> n;
	int m = n * 2;
	for(int i = 0 ; i < n ; i++)
	{
		int x ;  cin >> x;
		ar[x] = 1;
	}
	fac[0] = fac[1] = frev[0] = frev[1] = 1;
	for(int i = 2 ; i < maxl ; i++)
	{
		fac[i] = 1LL * fac[i - 1] * i % mod;
		frev[i] = mpo(fac[i] , mod - 2);
	}
	m2[0] = 1;
	for(int i = 1 ; i < maxn ; i++)  m2[i] = m2[i - 1] * 2 % mod;
	f[0] = 1;
	for(int i = 1 ; i < maxn ; i++)
	{
		for(int j = 0 ; 2 * j <= i ; j++)
		{
			int tmp = (C(2 * j , j) - C(2 * j , j - 1) + mod) % mod;
			tmp = 1LL * tmp * C(i , 2 * j) % mod;
			tmp = 1LL * tmp * m2[i - 2 * j] % mod;
			tmp = 1LL * tmp * fac[i] % mod;
			f[i] = (f[i] + tmp) % mod;
		}
	}

	if(ar[m] == 0)  
	{
		cout << 0 << endl;  return 0;
	}
	int cntz = 0 , cnto = 1;
	dp[m][0] = 1;  dp[m][1] = 2;
	for(int i = m - 1 ; i > 0 ; i--)
	{
		if(ar[i] == 0)  cntz++;
		else cnto++;
		if(ar[i] == 0)
			for(int j = cntz ; j <= cnto ; j++)
				dp[i][j] = 1LL * dp[i + 1][j] * (j - cntz + 1) % mod;
		else
		{
			for(int j = cntz ; j <= cnto ; j++)
			{
				dp[i][j] = dp[i + 1][j];
				for(int k = cntz ; k < j ; k++)
				{
					int tmp = 1LL * f[j - k - 1] * C(cnto - k - 1 , j - k - 1) % mod;
					tmp = 1LL * tmp * (j - k + 1) % mod;
					tmp = 1LL * tmp * dp[i + 1][k] % mod;
					dp[i][j] = (dp[i][j] + tmp) % mod;
				}
			}
		}
	}
	int ans = mpo(m2[n] , mod - 2);
	ans = 1LL * ans * dp[1][n] % mod;
	cout << ans << endl;
	return 0;
}

Subtask #1
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 340 KB Output is correct
2 Correct 3 ms 340 KB Output is correct
3 Correct 2 ms 340 KB Output is correct
4 Correct 2 ms 340 KB Output is correct
5 Correct 2 ms 340 KB Output is correct
6 Correct 2 ms 340 KB Output is correct
7 Correct 2 ms 340 KB Output is correct
8 Correct 2 ms 340 KB Output is correct
9 Correct 2 ms 344 KB Output is correct
10 Correct 2 ms 340 KB Output is correct

Subtask #2
52.0 / 52.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 340 KB Output is correct
2 Correct 3 ms 340 KB Output is correct
3 Correct 2 ms 340 KB Output is correct
4 Correct 2 ms 340 KB Output is correct
5 Correct 2 ms 340 KB Output is correct
6 Correct 2 ms 340 KB Output is correct
7 Correct 2 ms 340 KB Output is correct
8 Correct 2 ms 340 KB Output is correct
9 Correct 2 ms 344 KB Output is correct
10 Correct 2 ms 340 KB Output is correct
11 Correct 3 ms 600 KB Output is correct
12 Correct 3 ms 596 KB Output is correct
13 Correct 3 ms 596 KB Output is correct
14 Correct 2 ms 340 KB Output is correct
15 Correct 2 ms 340 KB Output is correct
16 Correct 3 ms 596 KB Output is correct
17 Correct 3 ms 340 KB Output is correct
18 Correct 3 ms 596 KB Output is correct
19 Correct 4 ms 596 KB Output is correct
20 Correct 3 ms 596 KB Output is correct

Subtask #3
42.0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 340 KB Output is correct
2 Correct 3 ms 340 KB Output is correct
3 Correct 2 ms 340 KB Output is correct
4 Correct 2 ms 340 KB Output is correct
5 Correct 2 ms 340 KB Output is correct
6 Correct 2 ms 340 KB Output is correct
7 Correct 2 ms 340 KB Output is correct
8 Correct 2 ms 340 KB Output is correct
9 Correct 2 ms 344 KB Output is correct
10 Correct 2 ms 340 KB Output is correct
11 Correct 3 ms 600 KB Output is correct
12 Correct 3 ms 596 KB Output is correct
13 Correct 3 ms 596 KB Output is correct
14 Correct 2 ms 340 KB Output is correct
15 Correct 2 ms 340 KB Output is correct
16 Correct 3 ms 596 KB Output is correct
17 Correct 3 ms 340 KB Output is correct
18 Correct 3 ms 596 KB Output is correct
19 Correct 4 ms 596 KB Output is correct
20 Correct 3 ms 596 KB Output is correct
21 Correct 5 ms 3104 KB Output is correct
22 Correct 4 ms 3156 KB Output is correct
23 Correct 5 ms 3156 KB Output is correct
24 Correct 8 ms 3156 KB Output is correct
25 Correct 3 ms 340 KB Output is correct
26 Correct 4 ms 3156 KB Output is correct
27 Correct 2 ms 340 KB Output is correct
28 Correct 3 ms 3088 KB Output is correct
29 Correct 3 ms 340 KB Output is correct
30 Correct 482 ms 3136 KB Output is correct
31 Correct 247 ms 3072 KB Output is correct
32 Correct 335 ms 3120 KB Output is correct
33 Correct 423 ms 3080 KB Output is correct
34 Correct 225 ms 3108 KB Output is correct
35 Correct 333 ms 3164 KB Output is correct
36 Correct 412 ms 3076 KB Output is correct