Submission #421717

#	Time	Username	Problem	Language	Result	Execution time	Memory
421717		amunduzbaev	Tents (JOI18_tents)	C++14	100 / 100	373 ms	71216 KiB

tents

/* made by amunduzbaev */
 
//~ #include <ext/pb_ds/assoc_container.hpp>
//~ #include <ext/pb_ds/tree_policy.hpp>
#include "bits/stdc++.h"
 
using namespace std;
//~ using namespace __gnu_pbds;

#define ff first
#define ss second
#define pb push_back
#define mp make_pair
#define ub upper_bound
#define lb lower_bound
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(),x.rend()
#define NeedForSpeed ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define vv vector
#define mem(arr, v) memset(arr, v, sizeof arr)
#define int long long
 
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii; 
typedef vector<int> vii;
typedef vector<pii> vpii;
template<class T> bool umin(T& a, const T& b) { return a > b ? a = b, true : false; }
template<class T> bool umax(T& a, const T& b) { return a < b ? a = b, true : false; }
template<int sz> using tut = array<int, sz>;
void usaco(string s) { freopen((s+".in").c_str(),"r",stdin);  
	freopen((s+".out").c_str(),"w",stdout); NeedForSpeed }
//~ template<class T> using oset = tree<T, 
//~ null_type, less_equal<T>, rb_tree_tag, 
//~ tree_order_statistics_node_update> ordered_set;
 
const int N = 3e3+5;
const int mod = 1e9+7;
const ll inf = 1e18;
const ld Pi = acos(-1);
 
#define MULTI 0
int n, m, k, s, t, q, ans, res, a[N];
int dp[N][N];

int rec(int i, int E){
	if(i > n){
		if(E == m) return 0;
		return 1;
	}
	int& res = dp[i][E];
	if(~res) return res;
	res = rec(i+1, E);
	if(E) res = (res + rec(i+1, E-1) * E * 4) % mod;
	if(E && i+1 <= n) res = (res + rec(i+2, E-1) * E * (n-i)) % mod;
	if(E > 1) res = (res + rec(i+1, E - 2) * E *(E - 1) / 2) % mod;
	return res;
}

void solve(int t_case){
	mem(dp, -1);
	cin>>n>>m;
	cout<<rec(1, m)<<"\n";
}

signed main(){
	NeedForSpeed
	if(MULTI){
		int t; cin>>t;
		for(int t_case = 1; t_case <= t; t_case++) solve(t_case);
	} else solve(1);
	return 0;
}

Compilation message (stderr)

tents.cpp: In function 'void usaco(std::string)':
tents.cpp:32:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 | void usaco(string s) { freopen((s+".in").c_str(),"r",stdin);
      |                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tents.cpp:33:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |  freopen((s+".out").c_str(),"w",stdout); NeedForSpeed }
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52