oj.uz

Submission #43993

# Submission time Handle Problem Language Result Execution time Memory
43993 2018-03-29T09:32:17 Z zscoder Tents (JOI18_tents) C++17
100 / 100
 395 ms 76744 KB 
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
 
using namespace std;
using namespace __gnu_pbds;
 
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define fbo find_by_order
#define ook order_of_key
 
typedef long long ll;
typedef pair<ll,ll> ii;
typedef vector<int> vi;
typedef long double ld; 
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> pbds;
typedef set<ll>::iterator sit;
typedef map<ll,ll>::iterator mit;

const int MOD = 1e9 + 7;

int add(int a, int b)
{
	a+=b; while(a>=MOD) a-=MOD;
	return a;
}

int mult(int a, int b)
{
	return (a*1LL*b)%MOD;
}

int C[3111][3111];
int fact[6111];
int pow2[6111];
int ipow2[6111];
int modpow(int a, int b)
{
	int r=1;
	while(b)
	{
		if(b&1) r=mult(r,a);
		a=mult(a,a); b>>=1;
	}
	return r;
}

int choose(int a, int b)
{
	if(a<b) return 0;
	if(b==0) return 1;
	if(C[a][b]!=-1) return C[a][b];
	return (C[a][b] = add(choose(a-1,b-1), choose(a-1,b)));
}

int dp[3111][3111];

int solve(int a, int b)
{
	if(a==0) return 1;
	if(a<0||b<0) return 0;
	if(dp[a][b]!=-1) return dp[a][b];
	return (dp[a][b] = add(solve(a-1,b),add(mult(4*b, solve(a-1,b-1)), mult((b*(b-1))/2, solve(a-1,b-2)))));
}

int main()
{
	ios_base::sync_with_stdio(0); cin.tie(0);
	int n,m; cin>>n>>m;
	memset(C,-1,sizeof(C)); memset(dp,-1,sizeof(dp));
	fact[0]=1; pow2[0]=ipow2[0]=1;
	for(int i=1;i<=6001;i++)
	{
		pow2[i]=add(pow2[i-1],pow2[i-1]);
		ipow2[i] = modpow(pow2[i], MOD-2);
	}
	for(int i=1;i<=6001;i++) fact[i]=mult(fact[i-1],i);
	int ans=0;
	for(int i=0;i<=m;i++)
	{
		int coeff = mult(choose(m, i), mult(choose(n, 2*i), mult(fact[2*i], ipow2[i])));
		ans = add(ans, mult(coeff, solve(n - 2*i, m - i)));
	}
	ans=add(ans,MOD-1);
	cout<<ans<<'\n';
}

Subtask #1
48.0 / 48.0

# Verdict Execution time Memory Grader output
1 Correct 68 ms 76152 KB Output is correct
2 Correct 72 ms 76340 KB Output is correct
3 Correct 62 ms 76340 KB Output is correct
4 Correct 60 ms 76340 KB Output is correct
5 Correct 59 ms 76340 KB Output is correct
6 Correct 64 ms 76368 KB Output is correct
7 Correct 71 ms 76368 KB Output is correct
8 Correct 59 ms 76368 KB Output is correct
9 Correct 58 ms 76368 KB Output is correct
10 Correct 60 ms 76368 KB Output is correct
11 Correct 61 ms 76368 KB Output is correct
12 Correct 64 ms 76432 KB Output is correct

Subtask #2
52.0 / 52.0

# Verdict Execution time Memory Grader output
1 Correct 68 ms 76152 KB Output is correct
2 Correct 72 ms 76340 KB Output is correct
3 Correct 62 ms 76340 KB Output is correct
4 Correct 60 ms 76340 KB Output is correct
5 Correct 59 ms 76340 KB Output is correct
6 Correct 64 ms 76368 KB Output is correct
7 Correct 71 ms 76368 KB Output is correct
8 Correct 59 ms 76368 KB Output is correct
9 Correct 58 ms 76368 KB Output is correct
10 Correct 60 ms 76368 KB Output is correct
11 Correct 61 ms 76368 KB Output is correct
12 Correct 64 ms 76432 KB Output is correct
13 Correct 100 ms 76512 KB Output is correct
14 Correct 61 ms 76640 KB Output is correct
15 Correct 317 ms 76640 KB Output is correct
16 Correct 102 ms 76640 KB Output is correct
17 Correct 106 ms 76640 KB Output is correct
18 Correct 110 ms 76640 KB Output is correct
19 Correct 329 ms 76640 KB Output is correct
20 Correct 259 ms 76640 KB Output is correct
21 Correct 180 ms 76668 KB Output is correct
22 Correct 183 ms 76668 KB Output is correct
23 Correct 192 ms 76744 KB Output is correct
24 Correct 390 ms 76744 KB Output is correct
25 Correct 304 ms 76744 KB Output is correct
26 Correct 328 ms 76744 KB Output is correct
27 Correct 395 ms 76744 KB Output is correct