Submission #376574

#	Time	Username	Problem	Language	Result	Execution time	Memory
376574		MatheusLealV	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	64 ms	32364 KiB

kangaroo

#include <bits/stdc++.h>
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define rep(i, a, b) for (int i = (a); i < (b); ++i)
std::mt19937 rng((int) std::chrono::steady_clock::now().time_since_epoch().count());
using namespace std;

// #define int long long
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
ll mod = (1000000007LL);
inline ll Mod(ll a, ll b){return (a%b);}
inline ll poww(ll a, ll b){ll res = 1;while (b > 0){if(b & 1) res = (res * a)%mod;a = (a * a)%mod;b >>= 1;}return res;}
ll gcd (ll a, ll b) { while (b) { a %= b,swap(a, b);}return a;}
void read(vector<int> &w, int n){w.resize(n);for(int i = 0; i < n; i++) cin>>w[i];}
void print(vector<int> &w){for(int i =0; i < sz(w); i++){if(i == sz(w) - 1) cout<<w[i]<<"\n";else cout<<w[i]<<" ";}}
int prodmod(vector<int> w);
int summod(vector<int> w);
///CUIDADO COM MAXN
#define N 2010

int n, ini, fim;
ll dp[N][N];
ll solve(int i, int k){
	if(k < 0) return 0;
	if(i > n) return (k==1);
	if(dp[i][k] != -1) return dp[i][k];
	int ans = 0;
	if(i == ini or i == fim){
		ll newcomp = solve(i+1,k+1);
		ll ponta = solve(i+1,k);
		return (newcomp + ponta)%mod;
	}
	if(i > fim){
		ll newcomp = 1LL*solve(i + 1, k + 1)*(k-1);
		ll merge = 1LL*solve(i+1,k-1)*(k-1);
		return dp[i][k] = (newcomp + merge)%mod;
	}
	if(i > ini){
		ll newcomp = 1LL*solve(i+1,k+1)*k;
		ll merge = 1LL*solve(i+1, k -1)*(k-1);
		return dp[i][k] = (newcomp + merge)%mod;
	}
	ll newcomp = 1LL*solve(i+1,k+1)*(k+1);
	ll merge = 1LL*solve(i+1,k-1)*(k-1);
	return dp[i][k] = (newcomp + merge)%mod;
}
int32_t main(){
	ios::sync_with_stdio(false); cin.tie(0);
	
	cin>>n>>ini>>fim;
	if(ini>fim)swap(ini, fim);
	memset(dp,-1,sizeof dp);
	cout<<solve(1, 0)<<"\n";
}
/*
    CUIDADO COM MAXN, MOD, OVERFLOW 
    >Colocar (>DEFINE INT LONG LONG<) no inicio do template
    >mod = (1e9 + 7), por padrao (NAO ESQUECER DE ALTERAR)
    >NAO ESQUECER DEFINE INT LONG LONG
    > N = 1 ? 
*/
int summod(vector<int> w){int curr=0;for(int i=0;i<sz(w); i++){curr = (curr+w[i])%mod;if(curr<0)curr+=mod;}return curr;}
int prodmod(vector<int> w){int curr = 1;
for(int i = 0; i < sz(w); i++){if(w[i] >= mod) w[i] %= mod;curr = (curr * w[i]) % mod;if(curr < 0) curr += mod;}return curr;}

Compilation message (stderr)

kangaroo.cpp: In function 'll solve(int, int)':
kangaroo.cpp:33:6: warning: unused variable 'ans' [-Wunused-variable]
   33 |  int ans = 0;
      |      ^~~

• Subtask 1: 6 / 6
• Subtask 2: 30 / 30
• Subtask 3: 15 / 15
• Subtask 4: 49 / 49